Posts on Kenno's Open Note

How to manually force reconciliation of Argo CD ApplicationSet

Sat, 05 Sep 2026 00:00:55 +1000

To immediately trigger a manual refresh and force reconciliation of an Argo CD ApplicationSet, we can apply a specific refresh annotation directly to the ApplicationSet resource.

For example, the following command force reconcile the awesome-appset immediately:

➜ kubectl annotate applicationset awesome-appset -n argocd \
argocd.argoproj.io/application-set-refresh=true --overwrite

Sample output:

applicationset.argoproj.io/dokuwiki-appset annotated

What This Does Behind the Scenes

Bypasses Caches: Applying argocd.argoproj.io/application-set-refresh: "true" tells the ApplicationSet controller to immediately reconcile and completely bypass the repo-server revision cache for Git generators. [1] (https://github.com/argoproj/argo-cd/issues/27798)
Forces Re-evaluation: The controller will instantly re-evaluate all template generators to create, update, or remove the underlying Application resources as necessary

Enable Dark Mode on Firefox for dwm

Sat, 25 Apr 2026 15:58:43 +1000

It’s 2026 and I still run dwm on my laptop. I think at some point I’ll need to switch to another minimal tiling window manager running on Wayland.

Anyway, I want to share an easy way to enable dark mode on Firefox running on dwm without installing any additional plugins by using the about:config method.

Type about:config in the address bar
Search for ui.systemUsesDarkTheme, and set it to 1

Reference:

https://major.io/p/enable-dark-mode-in-firefox/

Print Only Text Following a Match

Fri, 27 Mar 2026 17:17:59 +1100

I have the following text in a file called n8n-deployment:

...
          image: busybox:1.36
          image: docker.io/n8nio/n8n:2.13.4
          imagePullPolicy: IfNotPresent
...

And I want to use Regex search and match the version of n8n, in this case 2.13.4 should be output.

Here’s how this can be done using Ripgrep (rg) command.

➜ rg -N -o -P 'image.*n8n:\K.*$' n8n-deployment.yaml
2.13.4

Another way to do this is:

➜ rg -oN 'image.*n8n:(.*)' -r '$1' n8n-deployment.yaml
2.13.4

Or, with grep:

➜ grep -o -P 'image.*n8n:\K.*$' n8n-deployment.yaml
2.13.4

Explanation of flags:

Resolving Podman Error: Current System Boot ID Differs From Cached Boot ID

Sat, 17 Jan 2026 21:07:44 +1100

Recently, I noticed that whenever my server, banan, was rebooted, containers running under the git user did not automatically start.

❯ podman --version
podman version 5.6.0

❯ cat /etc/os-release
NAME="AlmaLinux"
VERSION="9.7 (Moss Jungle Cat)"
ID="almalinux"
ID_LIKE="rhel centos fedora"
VERSION_ID="9.7"
PLATFORM_ID="platform:el9"
PRETTY_NAME="AlmaLinux 9.7 (Moss Jungle Cat)"
ANSI_COLOR="0;34"
LOGO="fedora-logo-icon"
CPE_NAME="cpe:/o:almalinux:almalinux:9::baseos"
HOME_URL="https://almalinux.org/"
DOCUMENTATION_URL="https://wiki.almalinux.org/"
BUG_REPORT_URL="https://bugs.almalinux.org/"

ALMALINUX_MANTISBT_PROJECT="AlmaLinux-9"
ALMALINUX_MANTISBT_PROJECT_VERSION="9.7"
REDHAT_SUPPORT_PRODUCT="AlmaLinux"
REDHAT_SUPPORT_PRODUCT_VERSION="9.7"
SUPPORT_END=2032-06-01

Let’s investigate and fix this issue.

After switching to the git user, I encountered the following error when trying to list the running containers:

How to undo a pushed commit

Sat, 20 Dec 2025 01:33:59 +1100

Oops… I just accidentally pushed a git commit containing code with a secret in plain text to a remote repo! Though it’s a private repository, I want to clean this mess up for security best practice. So, let’s fix it!

Here are the last two commits. The secret resides in one of the files from the “add argocd infra to git” commit.

$ git log -2
commit fe7b0510edc4fb160a16421352ba598e3f62703e (HEAD -> main, origin/main, origin/HEAD)
Author: kenno <kenno@example.com>
Date:   Sat Dec 20 00:59:36 2025 +1100

    add argocd infra to git
    
commit c5a75ae14cf3528db1fea7677e2bdb54167037cd
Author: kenno <kenno@example.com>
Date:   Thu Dec 18 14:38:17 2025 +1100

    add basic auth middleware to longhorn httproute

Since the commit had already been pushed to a remote repository, simply “undoing” the commit locally is not enough; it is required to overwrite the remote history.

Podman Quadlet Volume Ownership

Sun, 14 Dec 2025 22:39:33 +1100

This is a short note that serves as a self-reminder on how podman can automatically change the ownership of a source volume to match the default UID and GID within the container.

TL;DR: Use the :U suffix on the volume definition.

The following is an example of the issue I had and how to apply the fix.

First, let’s list the current ownership of the directory to be used as the source volume for the container.

How I Resized My Linux Boot Partition

Fri, 31 Oct 2025 20:01:13 +1100

I recently ran into a classic problem on my long-running Fedora installation: my /boot partition was full. Back when I set up the system (around Fedora 20), 400MiB was more than enough. Now, with modern kernels, it can barely hold two versions, let alone the default three that Fedora manages. This meant I couldn’t run system updates.

The challenge was that my disk was partitioned with /dev/sda1 for /boot and /dev/sda2 as a single large LVM physical volume for my /root and /home filesystems. This setup prevents a simple resize of /dev/sda1.

Find what package provides a file with pacman

Sat, 11 Oct 2025 12:20:53 +1100

While running an Ansible playbook on one of my servers from an Arch device, I encountered the following error:

TASK [Gathering Facts] *****************************************************************************************************************************************************
[ERROR]: Task failed: Failed to connect to the host via ssh: ssh_askpass: exec(/usr/lib/ssh/ssh-askpass): No such file or directory
Host key verification failed.

It looks like the /usr/lib/ssh/ssh-askpass file doesn’t exit. To find out what package the missing file comes from, we can use pacman -F or pacman --files.

Set number of ReplicaSets to keep for k8s Deployment

Sun, 05 Oct 2025 16:26:57 +1100

By default, the Deployment in Kubernetes retains 10 ReplicaSets [1]. This number can be configured by setting the .spec.revisionHistoryLimit to a desired number.

The following is an example on how to retain just 3 old ReplicaSets in my ‘’n8n’’ Deployment.

➜ k get replicasets -n n8n
NAME             DESIRED   CURRENT   READY   AGE
n8n-57c89d6b7d   0         0         0       91d
n8n-5f9fb9c459   0         0         0       80d
n8n-666b9476f    0         0         0       80d
n8n-66cd6bd8c6   1         1         1       74d
n8n-6888cc89bd   0         0         0       91d
n8n-7466c456f8   0         0         0       91d
n8n-74dfd6cb8c   0         0         0       80d
n8n-f8f8f6d7b    0         0         0       237d

Let set .spec.revisionHistoryLimit to 3:

Communicate from a rootless container to the host

Sun, 28 Sep 2025 16:49:13 +1000

Occasionally, I need to communicate from a podman container to its host, and I keep forgetting how to that. I know I can always google it, but from what had happened earlier today, having a short note to remind myself how this can be easily done is much preferable in my opinion.

To communicate between the container and its host, we can just simply use host.containers.internal or host.docker.internal to refer to the host.

How to Rename a ZFS Pool

Wed, 30 Jul 2025 21:01:42 +1000

I’ve been a happy ZFS user for years, appreciating its robustness and features. Yet, in all that time, I’d never had to rename a pool. That changed today. Whether it’s for better organization, a server migration, or just because you’ve had a change of heart about a name, renaming a ZFS pool is a task that might pop up when you least expect it.

I needed to rename my pool from anime35 to anime36. I was pleasantly surprised to find the process is incredibly simple and elegant, which is what I’ve come to expect from ZFS.

Removing a broken RPM package on Fedora

Tue, 06 May 2025 10:36:30 +1000

While I was performing an upgrade of Fedora 41 to 42 on my laptop, I noticed there was package installed since Fedora 38. This package, zfs-dkms-2.2.0-1.fc38.noarch, needed to be removed as it blocked this Fedora 42 upgrade.

TL;DR - The solution is to use --noscripts option with rpm command. If you want to see how the zfs-dkms package removed, follow along.

Here’s the info about the package:

root@benjo:/etc/yum.repos.d# dnf info zfs-dkms
Updating and loading repositories:
Repositories loaded.
Installed packages
Name            : zfs-dkms
Epoch           : 0
Version         : 2.2.0
Release         : 1.fc38
Architecture    : noarch
Installed size  : 56.9 MiB
Source          : zfs-dkms-2.2.0-1.fc38.src.rpm
From repository : zfs
Summary         : Kernel module(s) (dkms)
URL             : https://github.com/openzfs/zfs
License         : CDDL
Description     : This package contains the dkms ZFS kernel modules.
Vendor          : <NULL>

Available packages
Name           : zfs-dkms
Epoch          : 0
Version        : 2.3.2
Release        : 1.fc41
Architecture   : noarch
Download size  : 31.0 MiB
Installed size : 58.6 MiB
Source         : zfs-dkms-2.3.2-1.fc41.src.rpm
Repository     : zfs
Summary        : Kernel module(s) (dkms)
URL            : https://github.com/openzfs/zfs
License        : CDDL
Description    : This package contains the dkms ZFS kernel modules.
Vendor

Let’s try to remove it normally:

ArgoCD CLI failed to invoke grpc call

Tue, 11 Mar 2025 20:24:00 +1100

When running argocd CLI, the following warning message shown:

➜ argocd app list
WARN[0000] Failed to invoke grpc call. Use flag --grpc-web in grpc calls. To avoid this warning message, use flag --grpc-web.
NAME  CLUSTER  NAMESPACE  PROJECT  STATUS  HEALTH  SYNCPOLICY  CONDITIONS  REPO  PATH  TARGET

To suppress this warning message, re-run the login with --grpc-web option. For example:

➜ argocd login argocd.apps.tuaf.local.cluster --grpc-web
Username: admin
Password:
'admin:login' logged in successfully
Context 'argocd.apps.tuaf.local.cluster' updated

➜ argocd app list
NAME  CLUSTER  NAMESPACE  PROJECT  STATUS  HEALTH  SYNCPOLICY  CONDITIONS  REPO  PATH  TARGET

Reference:

How to revert a single file to its state in main in branch

Fri, 28 Feb 2025 15:19:48 +1100

I want to reset a file stored in a git repo to its state as the main branch, and I kept forgetting how to do this.

So here is how, just to remind my future self.

➜ git status
On branch main
Your branch is up to date with 'origin/main'.

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
        modified:   kube-prometheus-stack-values.yaml

no changes added to commit (use "git add" and/or "git commit -a")

The above output shows that there is a modified file, kube-prometheus-stack-values.yaml that is not yet staged for commit.

Setting Retention for Kube Prometheus Stack

Tue, 25 Feb 2025 10:42:41 +1100

When deploying the prometheus-community/kube-prometheus-stack in a k8s cluster, the default retention for Prometheus scrapped data is 10d at the time of this writing or Helm chart kube-prometheus-stack-69.4.1. As a result, the longhorn storage is filled up fast, and caused the Prometheus to crash.

So I’d decided to change the retention period to 3 days, and also set retention size to 4GB. To do this, update the values file for the Helm chart with the following values:

How to reset account password for Xen Orchestra

Sat, 08 Feb 2025 15:20:38 +1100

This is a quick note on how to reset the password of user account on the open sourced Xen Orchestra.

To reset the password of a user, of course, you’d need to know the user account, e.g. admin@admin.net.

[root@xoa1 xo-server]# cd /opt/xo/xo-server
[root@xoa1 xo-server]# ./dist/recover-account-cli.mjs --help

xo-server-recover-account <user name or email>

    If the user does not exist, it is created, if it exists, updates
    its password, remove any configured OTP and resets its permission to Admin.

[root@xoa1 xo-server]# ./dist/recover-account-cli.mjs admin@admin.net
Password (leave empty for random): *******
user admin@admin.net has been successfully updated

However, if you also forgot the account itself, you can create a new user with the same command. Here is an example to create a new account called admin:

Running container with Podman Quadlet

Tue, 17 Dec 2024 11:06:41 +1100

Up until recently, my preferred method of creating Podman containers is to use Ansible, and that has been working fine for me. However, I just stumble the new-to-me method called “quadlet”. So far, I really like it, and already started moving some containers to quadlet.

To learn more about Quadlet, check out [1]. But, today I’m going to share an example of creating a simple container with Quadlet.

In this example, the container whoami is run in rootless mode, under a non-privileged user.

How to import ZFS pool with duplicated pool names

Sat, 14 Dec 2024 18:32:22 +1100

If you use ZFS as the file system, you probably already know that tank is the most common name for ZFS pools. That also applies to me, I do name most of my ZFS pools as tank as the default. There is no issue with that name, however, since ZFS’s pool name must be unique, this means I couldn’t import or have multiple ZFS pools with the name tank on a system.

How to enable and check linger for a systemd user

Tue, 03 Dec 2024 23:22:06 +1100

“The systemd login manager will terminate any user services when their login session ends unless you enable user lingering with the enable-linger option. Use loginctl with the enable-linger option to configure a user to start during the boot process and prevent the systemd service from terminating when the user session ends.” [1]

To enable linger for a user, e.g. kenno, we can run the following command:

# loginctl enable-linger kenno

I usually ran the above command, and that was it. However, today I need to check whether the user kenno had linger enabled already. I also want to document this for my own future reference.

Accessing host from inside Podman 5.0 container

Mon, 02 Dec 2024 20:47:20 +1100

Sometimes you need to connect to the host from a Podman container running on it. How would you do that?

In the past I was able to get this working by connecting to the gateway IP of the container. For example, I have a web server running on the host listening on port 8080.

➜ nc -vz localhost 8080
Ncat: Version 7.92 ( https://nmap.org/ncat )
Ncat: Connected to 127.0.0.1:8080.
Ncat: 0 bytes sent, 0 bytes received in 0.02 seconds.

Next, create a new container to run curl for testing.

Expand ZFS partition to use entire disk

Tue, 12 Nov 2024 10:09:20 +1100

This is just a quick note to jot down what I did to resize and expand a ZFS partition to entire disk. I never had to do this before; it tured out it was quite easy.

First ensure that the autoexpand option is set on the zpool. Then, stop the VM in order to resize the disk volume.

[root@phnomaural ~]# zpool set autoexpand=on immich

[root@phnomaural ~]# poweroff
[root@phnomaural ~]# Connection to phnomaural closed by remote host.

The original size of ZFS disk was 256 GiB, and it has been increased to 512 GiB. This was done by stopping the VM running on XCP-ng, and go to the disk and change the size to 256 GiB.

Fix container to container DNS lookup failed in Podman OpenSUSE Leap 15.16

Mon, 11 Nov 2024 16:06:07 +1100

I’ve started to running more containers in my homelab with Podman, running inside AlamaLinux. Most of the times, things just worked. However today, I tried to setup similar containers on OpenSUSE Leap 15.16 host, and I came across an issue getting containers to communicate with one another. Well, spoiler alert, I found a solution, hence this blog post.

TL;DR - install cni-plugin-dnsname package from cni-plugin-dnsname build service. (No package from the official OpenSUSE repo).

NGINX 413 Request Entity Too Large

Mon, 04 Nov 2024 23:00:50 +1100

While trying to upload a file to a web app using NGINX as a reverse proxy, I encountered the following error:

...
Save(<data/c5ceb2d914>) returned error, retrying after 19.847451977s: client.PutObject: <html>Documents/Fonts/FiraCode.zip
<head><title>413 Request Entity Too Large</title></head>
<body>
<center><h1>413 Request Entity Too Large</h1></center>
<hr><center>nginx/1.20.1</center>
</body>
</html>
Save(<data/d194099394>) returned error, retrying after 36.899440019s: client.PutObject: <html>Documents/Fonts/FiraCode.zip
<head><title>413 Request Entity Too Large</title></head>
<body>
<center><h1>413 Request Entity Too Large</h1></center>
<hr><center>nginx/1.20.1</center>
</body>
</html>
...

It turned out that NGINX has default value for file upload limit to 1 MB set in client_max_body_size variable. Therefore, I need to increase the file upload size to something bigger, says 50 MB. Where to update this file? Well, we can apply this change to the main NGINX’s configuration file, e.g. /etc/nginx/nginx.conf or specifically in the configuration file for the web app. I chose the latter for my case.

Look up one own's public IP easily

Mon, 28 Oct 2024 21:19:50 +1100

Occasionally, I need to look up my own public IP for various reasons. To do this, I would google “what is my ip”, and got a result on the browser.

Recently, I found a way to easily do this using curl command to an easy to remember URL ifconfig.io.

Here is an example, of course with the fake IPs as the results:

➜ curl ifconfig.io
2444:3444:20a:5310:d6c9:ffff:fef1:7777

To get the IPv4, we can supply the -4 option to curl command:

Installing Nerd Font on Fedora

Sun, 22 Sep 2024 16:24:42 +1000

I want to install ‘Hack Nerd Font’ on my laptop running Fedora 40. As of today, there is no RPM package that I am aware of that provides this font. Therefore, I would need to download and install the font manually.

Visit the Nerd font website, to choose a preferred font.
I like Hack Nerd Font. It can be downloaded from the Download link.
Unzip the downloaded (e.g. Hack.zip) and move or copy the directory to ~/.local/share/fonts directory.
Run fc-cache -fv to refresh the font cache.

Here is now the above steps are performed using command line:

Resizing a root partition on Linux VM

Mon, 16 Sep 2024 18:10:13 +1000

Well, I recently learned that one of my VMs had its root partition full. The following document on the root partition was resized on that VM.

It’s not gonna be something exciting or anything special. However, I feel like I should document anyway, in case I forget on how to do that in the future, and partly due to I no longer work with these type of work as my daily job anymore.

Replacing cron with systemd timer

Tue, 03 Sep 2024 16:15:58 +1000

Well, I don’t currently really have a good reason to replace a working cron job with systemd-timer beside practicing it.

The following is the existing cron task for www-data user. I want to convert this cron to a systemd-timer:

$ sudo crontab -l -u www-data

# m h  dom mon dow   command
*/5 * * * * php -f /var/www/nextcloud/cron.php

The above output indicates that the command php -f /var/www/nextcloud/cron.php is run at every 5th minute, of course by www-data user.

Upgrading Longhorn with Helm

Fri, 23 Aug 2024 13:55:07 +1000

For my test Kubernetes cluster, Longhorn is used as the persistent block storage. The installed version is 1.6.2, and the version 1.7.0 is available now. So today, I’m going to share how to perform the Longhorn upgrade using Helm.

I’m going to try to do this live as usual. Of course, I already created snapshots for all my K8s nodes in case thing goes south.

First, let’s verify the current installed version of Longhorn [1].

How to rebuild initramfs on Fedora

Wed, 21 Aug 2024 21:42:21 +1000

Earlier today while performing the update on my Fedora desktop, I encountered an issue with the new kernel update. As a result, the initramfs was not generated for the new installed kernel. So, I’ll share with you how to rebuild or generate the initramfs while fixing real issue on my Fedora workstation.

First, here is an output showing the source of the issue. It might not be clear of what’s going on, but that’s okay as it’s not the main focus of this blog post.

Process Life Cycle

Sat, 03 Aug 2024 10:01:12 +1000

A short while back, I had to do a revision about process life cycle in the operating system, Linux specifically. Last time that I had to learn about this topic was back in the good old days in college.

I don’t know when I need to review it again, so I think it’s a good idea to dump what I’ve learned including the references to this topic. Also, I will only focus mainly on the 5-state model.

Snapshot of LVM logical volume - a brief howto

Fri, 26 Jul 2024 11:33:26 +1000

Recently, after an OS updated and rebooted, I was not able to login to the desktop environment. When that happened, I thought to myself, “I wish I could just do a quick EBS snapshot like I would on the cloud before running any OS updates.”

On my Linux desktop, the root volume is an LVM volume, I knew that snapshot was possible, but never tried to create one before. A friend at work encouraged that I should make use of it, and it was not that hard to get started. Well, let’s see how it goes as I’m about to explore how LVM snapshot works on my desktop.

Systemctl cat is cool

Sat, 20 Jul 2024 12:41:32 +1000

Sometimes we want to see the content of a Systemd unit file. One obvious way to do it is to just cat/vim the content of the unit file directly.

For example, to display the content of systemd-tmpfiles-clean.timer, we can perform the following step:

➜ systemctl status systemd-tmpfiles-clean.timer | grep Loaded
     Loaded: loaded (/usr/lib/systemd/system/systemd-tmpfiles-clean.timer; static)

➜ cat /usr/lib/systemd/system/systemd-tmpfiles-clean.timer;
#  SPDX-License-Identifier: LGPL-2.1-or-later
#
#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.

[Unit]
Description=Daily Cleanup of Temporary Directories
Documentation=man:tmpfiles.d(5) man:systemd-tmpfiles(8)
ConditionPathExists=!/etc/initrd-release

[Timer]
OnBootSec=15min
OnUnitActiveSec=1d

But, can we do better than manually looking up the unit file and read it? Sure, can!

SELinux revision note

Sat, 20 Jul 2024 02:06:28 +1000

Today, I decided to have a quick revision on SELinux as it’s been a long while that I worked on any projects that required my attention to fiddling with SELinux.

While I was looking for an sealert in /var/log/messages on my Fedora based desktop, I found a real issue that I need to fix. Like most of my blog posts, I’d like to start writing the post while I was about to solve the issue.

How to test UDP port connectivity

Wed, 17 Jul 2024 20:13:16 +1000

Earlier today, I have a need to check for a UDP opening port on a remote Linux server. And I felt blank in my brain, like I never done this before. Then I remember with TCP, I could use nc command to check it. Something like:

➜ nc -vz opnsense 22
Ncat: Version 7.92 ( https://nmap.org/ncat )
Ncat: Connection to 2400:a888:333:0:222:ffff:fe54:67de failed: TIMEOUT.
Ncat: Trying next address...
Ncat: Connection to 192.168.1.1 failed: TIMEOUT.
Ncat: Trying next address...
Ncat: TIMEOUT.

The above output indicates that there is a failed connection between my computer to the remote host ‘opnsense’ on port 22.

Axum custom request extractor and validator using FromRequest

Fri, 12 Jul 2024 16:41:07 +1000

This post documents what I learned about creating custom Axum extractor which can be used with the validator for validation.

Create a new test project:

➜ cargo new request-validator
cd request-validator

The first crate to be added is axum for Axum framework.

request-validator on  main [?] via 🦀 v1.79.0
➜ cargo add axum
    Updating crates.io index
      Adding axum v0.7.5 to dependencies
             Features:
             + form
             + http1
             + json
             + matched-path
             + original-uri
             + query
             + tokio
             + tower-log
             + tracing
             - __private_docs
             - http2
             - macros
             - multipart
             - ws
    Updating crates.io index
     Locking 82 packages to latest compatible versions
...

We also need tokio crate that works together with axum.

How to force kill a Podman container

Sun, 07 Jul 2024 22:43:12 +1000

There is a container that I cannot stop. TL;DR the solution that worked for me was rebooting the host system.

Anyhow, I’ll share the troubleshooting steps that did not work.

❯ podman stop semaphore-postgres
WARN[0010] StopSignal SIGINT failed to stop container semaphore-postgres in 10 seconds, resorting to SIGKILL
Error: given PID did not die within timeout

❯ podman ps -a | grep semaphore-postgres
a688a42c4c15  docker.io/library/postgres:16              postgres              17 minutes ago  Stopping               0.0.0.0:3000->3
000/tcp                          semaphore-postgres

Instead of “If at first you can’t stop a container, try, try again”, can we just kill it?

How to find instance Id from the instance metadata

Sun, 07 Jul 2024 17:07:26 +1000

For instances which use version 2 of instance metadata, IMDSv2, run the following 2 commands:

[ec2-user@ip-172-31-45-35 ~]$ TOKEN=`curl -X PUT "http://169.254.169.254/latest/api/token" -H "X-aws-ec2-metadata-token-ttl-seconds: 21600"`
[ec2-user@ip-172-31-45-35 ~]$ curl -w "\n" -H "X-aws-ec2-metadata-token: $TOKEN" http://169.254.169.254/latest/meta-data/instance-id
i-04bd6066612345678

If you use IMDsv1, then there is no need generate the TOKEN value first, just query the instance-id directly:

[ec2-user@ip-172-31-45-35 ~]$ curl -w "\n" http://169.254.169.254/latest/meta-data/instance-id

In my case, it returned nothing as my EC2 instances uses IMDsV2. Oh, by the way, are you aware of -w or --write-out flag for curl? It’s pretty cool, you can use it to inject a newline character e.g. "\n" to the end of output from the curl command.

How to initiate Session Manager session using CLI

Fri, 05 Jul 2024 22:36:13 +1000

Tonight I want to connect to an EC2 instance that resides in a private subnet. I currently don’t have a bastion host I can use as an intermediary to jump to this instance. Well, as you might have guessed from this post’s title, the AWS Session Manager is something that might be helpful in this case. So, join me in this journey to configure and set up the Session Manager, using AWS CLI only.

Delete ElastiCache Redis Cluster Using AWS CLI

Wed, 03 Jul 2024 21:46:56 +1000

Once upon a time there exist an ElastiCache Redis cluster that I no longer needed. I know that the cluster could be deleted via ElastiCache web console. However, as a command-line addict as myself, I wanted to use AWS CLI to delete the cluster instead.

Well, actually this is my first time trying to delete an ElastiCache cluster using the CLI. I’m going to try to document how I do this, and what mistakes I’d make a long the way. The cluster name is called ‘my-test-cluster’. Let’s get started

Get connection status for a managed node with AWS CLI

Wed, 26 Jun 2024 14:04:44 +1000

I kept forgetting about the AWS CLI which is quite handy to quickly check if SSM is working on an EC2 instance.

So here it is again for my future-self. Use get-connection-status to return the connection status of the specified managed instance.

$ aws ssm get-connection-status --target i-092af3b3c1234567

{
  "Status": "connected",
  "Target": "i-092af3b3c1234567"
}

Reference:

get-connection-status

PostgreSQL FATAL: Peer Authentication Failed for User Postgres

Fri, 21 Jun 2024 14:43:35 +1000

Recently, I upgraded a server running Ubuntu 22.04 to 24.04, that also comes with PostgreSQL 16. For some odd reasons, the Postgres server was not managed by Ansible, and changes previously made to Postgres 15 was not recorded.

I noticed that the backup database (pg_dump) was not working properly, the backup database size was just a few kilobytes. Let’s investigate, shall we?

root@toto:/etc/cron.daily# ./postgresql-backup
pg_dump: error: connection to server on socket "/var/run/postgresql/.s.PGSQL.5432" failed: FATAL:  Peer authentication failed for user "postgres"

You might be wondering, what’s in postgresql-backup? Well, nothing fancy.

Postgres: Getting Permission Denied for Schema Public

Fri, 21 Jun 2024 00:19:52 +1000

I recently upgraded the PostgreSQL server on one my server from version 14 to 16. Why the big jump? This was due to the OS running on this server was upgraded from Ubuntu 22.04 to 24.04.

When the database was restored from the database dump, the application that requires that the database detects the new version and tried to perform the database migration. That’s when it failed and produced the following error message:

How to use auto-update in Podman

Sat, 15 Jun 2024 18:42:35 +1000

I have a Podman container that needs periodically manual update once in a while. I’d like this container to auto-update, and found that this was possible with podman auto-updates feature.

Essentially, I need to set a label for the container - --label io.containers.autoupdate=registry. More details with and very good explanation about this topic is available at a Red Hat Enable Sysadmin article titled “How to use auto-updates and rollbacks in Podman”.

How to upgrade openSUSE 15.5 to 15.6 using the cli

Wed, 12 Jun 2024 22:44:09 +1000

The following note shows how to use Zypper to do a live distribution upgrade of openSUSE Leap 15.5 to openSUSE Leap 15.6.

thounchey3:~ # cat /etc/os-release
NAME="openSUSE Leap"
VERSION="15.5"
ID="opensuse-leap"
ID_LIKE="suse opensuse"
VERSION_ID="15.5"
PRETTY_NAME="openSUSE Leap 15.5"
ANSI_COLOR="0;32"
CPE_NAME="cpe:/o:opensuse:leap:15.5"
BUG_REPORT_URL="https://bugs.opensuse.org"
HOME_URL="https://www.opensuse.org/"
DOCUMENTATION_URL="https://en.opensuse.org/Portal:Leap"
LOGO="distributor-logo-Leap"

Check for the 3 required repositories, ensure they are enabled.`

thounchey3:~ # zypper lr -u
Repository priorities are without effect. All enabled repositories share the same priority.

#  | Alias                       | Name                                                                                        | Enabled | GPG Check | Refresh | URI
---+-----------------------------+---------------------------------------------------------------------------------------------+---------+-----------+---------+------------------------------------------------------------------------
 1 | repo-backports-debug-update | Update repository with updates for openSUSE Leap debuginfo packages from openSUSE Backports | No      | ----      | ----    | http://download.opensuse.org/update/leap/15.5/backports_debug/
 2 | repo-backports-update       | Update repository of openSUSE Backports                                                     | Yes     | (r ) Yes  | Yes     | http://download.opensuse.org/update/leap/15.5/backports/
 3 | repo-debug                  | Debug Repository                                                                            | No      | ----      | ----    | http://download.opensuse.org/debug/distribution/leap/15.5/repo/oss/
 4 | repo-debug-non-oss          | Debug Repository (Non-OSS)                                                                  | No      | ----      | ----    | http://download.opensuse.org/debug/distribution/leap/15.5/repo/non-oss/
 5 | repo-debug-update           | Update Repository (Debug)                                                                   | No      | ----      | ----    | http://download.opensuse.org/debug/update/leap/15.5/oss/
 6 | repo-debug-update-non-oss   | Update Repository (Debug, Non-OSS)                                                          | No      | ----      | ----    | http://download.opensuse.org/debug/update/leap/15.5/non-oss/
 7 | repo-non-oss                | Non-OSS Repository                                                                          | Yes     | (r ) Yes  | Yes     | http://download.opensuse.org/distribution/leap/15.5/repo/non-oss/
 8 | repo-openh264               | Open H.264 Codec (openSUSE Leap)                                                            | Yes     | (r ) Yes  | Yes     | http://codecs.opensuse.org/openh264/openSUSE_Leap/
 9 | repo-oss                    | Main Repository                                                                             | Yes     | (r ) Yes  | Yes     | http://download.opensuse.org/distribution/leap/15.5/repo/oss/
10 | repo-sle-debug-update       | Update repository with debuginfo for updates from SUSE Linux Enterprise 15                  | No      | ----      | ----    | http://download.opensuse.org/debug/update/leap/15.5/sle/
11 | repo-sle-update             | Update repository with updates from SUSE Linux Enterprise 15                                | Yes     | (r ) Yes  | Yes     | http://download.opensuse.org/update/leap/15.5/sle/
12 | repo-source                 | Source Repository                                                                           | No      | ----      | ----    | http://download.opensuse.org/source/distribution/leap/15.5/repo/oss/
13 | repo-update                 | Main Update Repository                                                                      | Yes     | (r ) Yes  | Yes     | http://download.opensuse.org/update/leap/15.5/oss/
14 | repo-update-non-oss         | Update Repository (Non-Oss)                                                                 | Yes     | (r ) Yes  | Yes     | http://download.opensuse.org/update/leap/15.5/non-oss/

thounchey3:~ # zypper refresh
Repository 'Update repository of openSUSE Backports' is up to date.
Repository 'Non-OSS Repository' is up to date.
Repository 'Open H.264 Codec (openSUSE Leap)' is up to date.
Repository 'Main Repository' is up to date.
Repository 'Update repository with updates from SUSE Linux Enterprise 15' is up to date.
Repository 'Main Update Repository' is up to date.
Repository 'Update Repository (Non-Oss)' is up to date.
All repositories have been refreshed.

thounchey3:~ # zypper update
Loading repository data...
Reading installed packages...
Nothing to do.

thounchey3:~ # grep baseurl /etc/zypp/repos.d/*.repo | grep -v releasever                                                     [1321/1321]
/etc/zypp/repos.d/repo-openh264.repo:baseurl=http://codecs.opensuse.org/openh264/openSUSE_Leap/

thounchey3:~ # zypper --releasever=15.6 refresh
Warning: Enforced setting: $releasever=15.6
Retrieving repository 'Update repository of openSUSE Backports' metadata ..........................................................[done]
Building repository 'Update repository of openSUSE Backports' cache ...............................................................[done]
Retrieving repository 'Non-OSS Repository' metadata ...............................................................................[done]
Building repository 'Non-OSS Repository' cache ....................................................................................[done]
Repository 'Open H.264 Codec (openSUSE Leap)' is up to date.                                                                             Retrieving repository 'Main Repository' metadata ..................................................................................[done]
Building repository 'Main Repository' cache .......................................................................................[done]
Retrieving repository 'Update repository with updates from SUSE Linux Enterprise 15' metadata .....................................[done]
Building repository 'Update repository with updates from SUSE Linux Enterprise 15' cache ..........................................[done]
Retrieving repository 'Main Update Repository' metadata ...........................................................................[done]
Building repository 'Main Update Repository' cache ................................................................................[done]
Retrieving repository 'Update Repository (Non-Oss)' metadata ......................................................................[done]
Building repository 'Update Repository (Non-Oss)' cache ...........................................................................[done]
All repositories have been refreshed.

thounchey3:~ # zypper --releasever=15.6 dup --download-in-advance
Warning: Enforced setting: $releasever=15.6
Loading repository data...
Reading installed packages...
Warning: You are about to do a distribution upgrade with all enabled repositories. Make sure these repositories are compatible before you
 continue. See 'man zypper' for more information about this command.
Computing distribution upgrade...

The following 163 packages are going to be upgraded:
  ansible apparmor-abstractions apparmor-parser apparmor-profiles bind-utils branding-openSUSE cracklib cracklib-dict-small
  crypto-policies curl dracut dracut-mkinitrd-deprecated e2fsprogs fipscheck firewalld fish gettext-runtime gio-branding-openSUSE
  girepository-1_0 git git-core glib2-tools glibc glibc-devel glibc-locale glibc-locale-base gpg2 grub2 grub2-branding-openSUSE
  grub2-i386-pc grub2-x86_64-efi haveged htop hwloc-data ipset jeos-firstboot kmod krb5 less libapparmor1 libargon2-1 libaugeas0
  libblkid1 libbsd0 libcom_err2 libcontainers-common libcontainers-default-policy libcrack2 libcryptsetup12 libcurl4 libdevmapper1_03
  libext2fs2 libfdisk1 libfido2-1 libfido2-udev libfipscheck1 libgcrypt20 libgio-2_0-0 libgirepository-1_0-1 libglib-2_0-0
...

...
dracut[I]: *** Stripping files ***
dracut[I]: *** Stripping files done ***
dracut[I]: *** Creating image file '/boot/initrd-6.4.0-150600.21-default' ***
dracut[I]: *** Creating initramfs image file '/boot/initrd-6.4.0-150600.21-default' done ***
Running post-transaction scripts ..................................................................................................[done]
There are running programs which still use files and libraries deleted or updated by recent upgrades. They should be restarted to benefit from the latest updates. Run 'zypper ps -s' to list these programs.

Since the last system boot core libraries or services have been updated.
Reboot is suggested to ensure that your system benefits from these updates.

reboot

❯ cat /etc/os-release
NAME="openSUSE Leap"
VERSION="15.6"
ID="opensuse-leap"
ID_LIKE="suse opensuse"
VERSION_ID="15.6"
PRETTY_NAME="openSUSE Leap 15.6"
ANSI_COLOR="0;32"
CPE_NAME="cpe:/o:opensuse:leap:15.6"
BUG_REPORT_URL="https://bugs.opensuse.org"
HOME_URL="https://www.opensuse.org/"
DOCUMENTATION_URL="https://en.opensuse.org/Portal:Leap"
LOGO="distributor-logo-Leap"

Reference:

Delete unused ENIs on AWS with AWS CLI

Sun, 09 Jun 2024 17:16:23 +1000

So I want to clean up Elastic Network Interfaces (ENIs) that were created for testing and no longer needed, and I want to use AWS CLI to do that.

For me, I know that all unused ENIs will have their status as “available”. So I will find all those ENIs and will delete them.

➜ aws ec2 describe-network-interfaces --filters Name=status,Values=available \
--query 'NetworkInterfaces[].{NetworkInterfaceId:NetworkInterfaceId,Description:Description}'
[
    {
        "NetworkInterfaceId": "eni-0dc616df583312345",
        "Description": "2nd nic in 2b az"
    },
    {
        "NetworkInterfaceId": "eni-0bf98b53cf1b12345",
        "Description": "2nd nic"
    },
    {
        "NetworkInterfaceId": "eni-034bcff8ceef12345",
        "Description": "test-eni"
    },
    {
        "NetworkInterfaceId": "eni-09adbc3a20c912345",
        "Description": "Test 2nd eni on custom subnet 2a AZ"
    }
]

Next, I need to feed each of the values of “NetworkInterfaceId” to the delete command aws ec2 delete-network-interface, which takes only 1 NetworkInterfaceId at a time.

Installing Xe Guest Utilities on OpenSUSE Leap 15.5

Sun, 02 Jun 2024 23:02:04 +1000

This is a quick note on how to install xe-guest-utilities on OpenSUSE Leap 15.5.

Unlike other distros like AlmaLinux where xe-guest-utilities is provided by EPEL repository, on OpenSUSE Leap, this package is available in the guest-tools.iso disk. At least, I was not able to find any similar package on OpenSUSE’s repositories which provide this Xe guest utilities.

Therefore, we first need to attach the guest-tools.iso disk to the VM.

On Xen Orchestra web ui, perform the following:

Wicked keeps DUID on OpenSuse 15 even when NIC is replaced

Fri, 31 May 2024 20:58:55 +1000

I have migrated a VM running on Proxmox to Xcpng host. Despite the imported VM on Xcpng has a new NIC with new MAC address, it still retained old IP address asssigned to the old MAC of the VM running on Proxmox. The VM is running OpenSUSE Leap 15.5 and use wicked for network management. How to fix this?

Spoiler alert, I figured out how to fix it.

First, let’s run some commands to display some information. Here, the new MAC address for eth0 NIC is 12:ea:4c:8f:34:f2. The IP addres 192.168.1.132 is allocated by DHCP service running on OPNsense router for a device with MAC 02:14:98:8a:c5:2c.

How to upgrade FreeBSD 13.2 to 14.0

Wed, 29 May 2024 22:24:45 +1000

I just found out that FreeBSD 13.2-RELEASE will be end-of-life support within 1 month time from now. It’s time to upgrade FreeBSD on one of nas boxes to 14.0-RELEASE. The following is to capture the steps used to perform the upgrade. It’s similar to my old post.

SSH into the server, and run tmux or screen. You really don’t want to lose SSH connection during the upgrade.

$ ssh kenno@nas2

$ tmux

Check the current running version of FreeBSD:

root@nas2:~ # freebsd-version
13.2-RELEASE-p11

Make sure the system is up-to-date with all the patches:

root@nas2:~ # freebsd-update fetch
root@nas2:~ # freebsd-update install

root@nas2:~ # pkg update
root@nas2:~ # pkg upgrade

Upgrade FreeBSD from 13.2 to 14.0

root@nas2:~ # freebsd-update -r 14.0-RELEASE upgrade
src component not installed, skipped
Looking up update.FreeBSD.org mirrors... 3 mirrors found.
Fetching metadata signature for 13.2-RELEASE from update1.freebsd.org... done.
Fetching metadata index... done.
Inspecting system... done.

The following components of FreeBSD seem to be installed:
kernel/generic kernel/generic-dbg world/base world/lib32

The following components of FreeBSD do not seem to be installed:
world/base-dbg world/lib32-dbg

Does this look reasonable (y/n)? y

Fetching metadata signature for 14.0-RELEASE from update1.freebsd.org... done.
Fetching metadata index... done.
Fetching 1 metadata patches. done.
Applying metadata patches... done.
Fetching 1 metadata files... done.
Inspecting system...

Wait for a long while… then when the update process detects changes in some important files, I’m asked to decide what to do by editing that file, pick the desired changes, and save them. For example:

The following changes, which occurred between FreeBSD 13.2-RELEASE and                                                                       [0/143]
FreeBSD 14.0-RELEASE have been merged into /etc/ssh/sshd_config:
--- current version
+++ new version
@@ -87,11 +87,11 @@
 #UsePAM yes

 #AllowAgentForwarding yes
 #AllowTcpForwarding yes
 #GatewayPorts no
-#X11Forwarding yes
+#X11Forwarding no
 #X11DisplayOffset 10
 #X11UseLocalhost yes
 #PermitTTY yes
 #PrintMotd yes
 #PrintLastLog yes
@@ -104,11 +104,11 @@
 #PidFile /var/run/sshd.pid
 #MaxStartups 10:30:100
 #PermitTunnel no
 #ChrootDirectory none
 #UseBlacklist no
-#VersionAddendum FreeBSD-20230719
+#VersionAddendum FreeBSD-20231004

 # no default banner path
 #Banner none

 # override default of no subsystems
Does this look reasonable (y/n)? y

The following changes, which occurred between FreeBSD 13.2-RELEASE and
FreeBSD 14.0-RELEASE have been merged into /etc/sysctl.conf:
--- current version
+++ new version
@@ -1,6 +1,5 @@
-# $FreeBSD$
 #
 #  This file is read when going to multi-user and its contents piped thru
 #  ``sysctl'' to adjust kernel values.  ``man 5 sysctl.conf'' for details.
 #

Does this look reasonable (y/n)? y
To install the downloaded upgrades, run "/usr/sbin/freebsd-update install".

Perform the update by running the above suggested command.

root@nas2:~ # /usr/sbin/freebsd-update install
src component not installed, skipped
Creating snapshot of existing boot environment... done.
Installing updates...
Kernel updates have been installed.  Please reboot and run
"/usr/sbin/freebsd-update install" again to finish installing updates.

I guess we know what to do next…

root@nas2:~ # reboot
Connection to nas2 closed by remote host.
Connection to nas2 closed.

Reconnect to the server with SSH. There is no need to run ’tmux’ session this time.

root@nas2:~ # /usr/sbin/freebsd-update install
src component not installed, skipped
Creating snapshot of existing boot environment... done.
Installing updates...rm: ///usr/include/c++/v1/__string: is a directory

Restarting sshd after upgrade
Performing sanity check on sshd configuration.
Stopping sshd.
Waiting for PIDS: 863.
Performing sanity check on sshd configuration.
Starting sshd.
Scanning /usr/share/certs/untrusted for certificates...
Scanning /usr/share/certs/trusted for certificates...

Completing this upgrade requires removing old shared object files.
Please rebuild all installed 3rd party software (e.g., programs
installed from the ports tree) and then run "/usr/sbin/freebsd-update install"
again to finish installing updates.

How to rebuild all installed 3rd party software? I’m guessing I need to run pkg update && pkg upgrade.

root@nas2:~ # pkg update
pkg: Warning: Major OS version upgrade detected.  Running "pkg bootstrap -f" recommended
Updating FreeBSD repository catalogue...
pkg: Repository FreeBSD has a wrong packagesite, need to re-create database
Fetching meta.conf: 100%    178 B   0.2kB/s    00:01
Fetching data.pkg: 100%    7 MiB   3.6MB/s    00:02
Processing entries: 100%
FreeBSD repository update completed. 34072 packages processed.
All repositories are up to date.

Love the suggestion about running pkg bootstrap -f.

root@nas2:~ # pkg bootstrap -f
The package management tool is not yet installed on your system.
Do you want to fetch and install it now? [y/N]: y
Bootstrapping pkg from pkg+http://pkg.FreeBSD.org/FreeBSD:14:amd64/quarterly, please wait...
Verifying signature with trusted certificate pkg.freebsd.org.2013102301... done
Installing pkg-1.21.3...
package pkg is already installed, forced install
Extracting pkg-1.21.3: 100%

This time, I should be able to continue updating the 3rd party software.

root@nas2:~ # pkg update
Updating FreeBSD repository catalogue...
FreeBSD repository is up to date.
All repositories are up to date.
root@nas2:~ # pkg upgrade
Updating FreeBSD repository catalogue...
FreeBSD repository is up to date.
All repositories are up to date.
Updating database digests format: 100%
Checking for upgrades (44 candidates): 100%
Processing candidates (44 candidates): 100%
The following 43 package(s) will be affected (of 0 checked):

Installed packages to be REINSTALLED:
        binutils-2.40_5,1 (ABI changed: 'freebsd:13:x86:64' -> 'freebsd:14:x86:64')
        bsdinfo-0.22_2 (ABI changed: 'freebsd:13:x86:64' -> 'freebsd:14:x86:64')
        btop-1.3.2 (ABI changed: 'freebsd:13:x86:64' -> 'freebsd:14:x86:64')
        dmidecode-3.5 (ABI changed: 'freebsd:13:x86:64' -> 'freebsd:14:x86:64')
...<SNIP>...
        tmux-3.3a_2 (ABI changed: 'freebsd:13:x86:64' -> 'freebsd:14:x86:64')
        tree-sitter-0.22.2 (ABI changed: 'freebsd:13:x86:64' -> 'freebsd:14:x86:64')
        unibilium-2.1.1_1 (ABI changed: 'freebsd:13:x86:64' -> 'freebsd:14:x86:64')
        zstd-1.5.6 (ABI changed: 'freebsd:13:x86:64' -> 'freebsd:14:x86:64')

Number of packages to be reinstalled: 43

395 MiB to be downloaded.

Proceed with this action? [y/N]: y

That’s it!

Rust cannot find derive macro `Serialize` in this scope

Wed, 22 May 2024 22:46:23 +1000

While trying out some Rust exercises, I came across the following error:

$ cargo run --bin iter2
   Compiling tutor-web-app-ssr v0.1.0 (/home/kenno/dev/rust/chapter7/ezytutors/tutor-web-app-ssr)
error: cannot find derive macro `Serialize` in this scope
  --> tutor-web-app-ssr/src/bin/iter2.rs:17:10
   |
17 | #[derive(Serialize, Deserialize)]
   |          ^^^^^^^^^
   |
note: `Serialize` is imported here, but it is only a trait, without a derive macro
  --> tutor-web-app-ssr/src/bin/iter2.rs:5:26
   |
5  | use serde::{Deserialize, Serialize};
   |                          ^^^^^^^^^

error: cannot find derive macro `Deserialize` in this scope
  --> tutor-web-app-ssr/src/bin/iter2.rs:17:21
   |
17 | #[derive(Serialize, Deserialize)]

<SNIP>

This happened because I didn’t specify the required dependency feature for serde crate. Here is what I had in Cargo.toml when the above error occurred:

How to generate Let's Encrypt SSL cert for Bitnami Lightsail

Wed, 22 May 2024 15:10:58 +1000

So you just setup a new shiny WordPress website on a Lightsail (WordPress) instance. Now, you’ve been told to setup an SSL certificate for your website domain. What to do? The following steps show how to generate a free SSL certificate provided by Let’s Encrypt.

bitnami@ip-172-26-12-25:~$ sudo /opt/bitnami/bncert-tool
----------------------------------------------------------------------------
Welcome to the Bitnami HTTPS Configuration tool.

----------------------------------------------------------------------------
Domains

Please provide a valid space-separated list of domains for which you wish to 
configure your web server.

Domain list []: lightsail.example.com

The following domains were not included: www.lightsail.example.com.
Do you want to add them? [Y/n]: n

Warning: No www domains (e.g. www.example.com) or non-www domains (e.g. www.example.com)
have been provided, so the following redirections will be disabled: non-www 
to www, www to non-www.
Press [Enter] to continue:

----------------------------------------------------------------------------
Enable/disable redirections

Please select the redirections you wish to enable or disable on your Bitnami installation.

Enable HTTP to HTTPS redirection [Y/n]: Y

----------------------------------------------------------------------------
Changes to perform

The following changes will be performed to your Bitnami installation:

1. Stop web server
2. Configure web server to use a free Let's Encrypt certificate for the domains: lightsail.example.com
3. Configure a cron job to automatically renew the certificate each month
4. Configure web server name to: lightsail.example.com
5. Enable HTTP to HTTPS redirection (example: redirect http://lightsail.example.com to https://lightsail.example.com)
6. Start web server once all changes have been performed

Do you agree to these changes? [Y/n]: Y

----------------------------------------------------------------------------
Create a free HTTPS certificate with Let's Encrypt

Please provide a valid e-mail address for which to associate your Let's Encrypt certificate.

Domain list: lightsail.example.com

Server name: lightsail.example.com

E-mail address []: validemail@example.com

The Let's Encrypt Subscriber Agreement can be found at:

https://letsencrypt.org/documents/LE-SA-v1.3-September-21-2022.pdf

Do you agree to the Let's Encrypt Subscriber Agreement? [Y/n]:

----------------------------------------------------------------------------
Performing changes to your installation

The Bitnami HTTPS Configuration Tool will perform any necessary actions to your Bitnami installation. 
This may take some time, please be patient.

----------------------------------------------------------------------------
Success

The Bitnami HTTPS Configuration Tool succeeded in modifying your installation.

The configuration report is shown below.

Backup files:
* /opt/bitnami/apache/conf/httpd.conf.back.202405220509
* /opt/bitnami/apache/conf/bitnami/bitnami.conf.back.202405220509
* /opt/bitnami/apache/conf/bitnami/bitnami-ssl.conf.back.202405220509
* /opt/bitnami/apache/conf/vhosts/wordpress-https-vhost.conf.back.202405220509
* /opt/bitnami/apache/conf/vhosts/wordpress-vhost.conf.back.202405220509

Find more details in the log file:

/tmp/bncert-202405220509.log

If you find any issues, please check Bitnami Support forums at:

https://github.com/bitnami/vms

Press [Enter] to continue:

That’s it.

Nvim Treesitter reinstalls parser every time Neovim starts

Sat, 18 May 2024 13:23:05 +1000

I’m in the process of migrating existing Neovim plugins managed by Packer to a new plugin manager called ‘Lazy’.

While setting the nvim-treesitter plugin, I came across this issue that nvim-treesitter keeps reinstalling all language parsers every time Neovim is started.

[nvim-treesitter] [5/5] Treesitter parse for vim has been installed

What happened? Well, it turns out this is is pretty much a common issue when you switching from Packer to Lazy plugin manager without cleaning up files and directories created by Packer according to this [1].

Adjusting Firefox DPI

Sat, 04 May 2024 21:33:15 +1000

On a few of my computers with 4K monitors running Linux, Firefox either display with tiny fonts or very large fonts, while most applications behave normally.

After searching for a work around, I found the following solution works for me: setting the layout.css.devPixelsPerPx to a smaller number, e.g. 0.7.

From this this page:

You can set layout.css.devPixelsPerPx to 1.0 (default is -1) on the about:config page. Adjust its value in 0.1 or 0.05 steps (1.1 to enlarge or 0.9 to reduce) until icons or text looks right. You may need values above 2.0 if you have a high resolution display but make sure not to use values too large or too small.

ipcalc - Perform simple operations on IP addresses and networks

Thu, 02 May 2024 22:37:48 +1000

Tonight I just stumbled on a command line tool or utility called ipcacl. This tool is used to perform operations on IP addresses and networks.

On Fedora, ipcalc is provided by ipcacl package. If you on a different distro, search for ipcaclc, there should be a similar package name.

➜ rpm -q ipcalc
ipcalc-1.0.3-9.fc40.x86_64

Here are some examples of what we can use this utility for, though I encourage you to run man ipcalc to learn more what you can do with it.

Deploy metrics-server in Kubernetes using Helm

Wed, 24 Apr 2024 01:20:00 +1000

This is a short note on how to install metrics-server using Helm on my k8s cluster.

$ kubectl version
Client Version: v1.29.3
Kustomize Version: v5.0.4-0.20230601165947-6ce0bf390ce3
Server Version: v1.29.3

$ helm version --short
v3.14.4+g81c902a

Before we can install the chart, we will need to add the metrics-server repo to Helm.

$ helm repo add metrics-server https://kubernetes-sigs.github.io/metrics-server/

Update the repo:

$ helm repo update
Hang tight while we grab the latest from your chart repositories...
...Successfully got an update from the "metrics-server" chart repository
Update Complete. ⎈Happy Helming!⎈

I also need to make a small customization to the chart’s default value since my k8s cluster uses self-signed certificates.

Connect to a Redis cluster with Python

Wed, 03 Apr 2024 22:27:50 +1100

To connect to a Redis server with Python, one can use python3-redis module.

First verify that python3-redis module is installed. I’m showing the package name in Fedora 39, if you use a different distro, then check for the relevant package name.

$ rpm -q python3-redis
python3-redis-4.3.3-1.el9.noarch

Here is the sample code to connect to a non-cluster Redis server:

import redis

# Connect to Redis
r = redis.Redis(host='10.97.147.175', port=6379)

# Set a key-value pair
r.set('my_key', 'Hello, Redis!')

# Get the value of the key
value = r.get('my_key')
print(value.decode('utf-8'))

If you want to connect to a Redis cluster (that has both master and replicas), use this version instead:

How to convert putty ppk to pem on macOS

Thu, 28 Mar 2024 17:03:00 +1100

Assuming that you use brew on your macOS, converting a ppk file to pem file is relatively easy.

Install putty on your mac

➜ brew install putty

Generate the key

➜ puttygen existing_key.ppk -O private-openssh -o new_key.pem

Here are the options used in above command:

-O private-openssh : save the output as a SSH-2 private key
-o new_key.pem : save the output to new_key.pem

Full credit go to this blog post [1], where I had learned to convert a PPK to PEM file.

How to deploy Uptime Kuma on kubernetes

Fri, 15 Mar 2024 18:39:02 +1100

I’ve been running Uptime Kuma on a podman-container for a long time with no problem. Recently, though, I’ve been running a mini Kubernetes cluster at home, and decided to move this conatainer to the same cluster.

The following is to document how I deploy Uptime Kuma on a Kubernetes cluster.

As I’m new to Kubernetes world, I broke down the tasks I need to do in 6 pieces:

$ ls -1
1.namespace.yaml
2.service.yaml
3.pvc.yaml
4.deployment.yaml
5.tls-secret.yaml
6.ingress.yaml

The first step is to create a new namespace for this application or deployment. It’ll be called ‘uptime-kuma’.

$ cat 1.namespace.yaml
kind: Namespace
apiVersion: v1
metadata:
  name: uptime-kuma

$ kubectl apply -f ./1.namespace.yaml

Create a new service, which will listen on port 3001.

$ cat 2.service.yaml
apiVersion: v1
kind: Service
metadata:
  name: uptime-kuma-svc
  namespace: uptime-kuma
spec:
  selector:
    app: uptime-kuma
  ports:
  - name: uptime-kuma
    port: 3001
    targetPort: 3001
    protocol: TCP

Next is to create a persistent volume claim for Uptime Kuma’s app data. Based on the current usage on my existing podman-container, 512 MiB is plenty. In my cluster, I use Longhorn as the persistent block storage.

$ cat 3.pvc.yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: uptime-kuma-pvc
  namespace: uptime-kuma
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: longhorn
  resources:
    requests:
      storage: 512Mi

Here is the deployment file.

$ cat 4.deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: uptime-kuma
  namespace: uptime-kuma
spec:
  selector:
    matchLabels:
      app: uptime-kuma
  replicas: 1
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 1
  template:
    metadata:
      labels:
        app: uptime-kuma
    spec:
      containers:
      - name: uptime-kuma
        image: louislam/uptime-kuma:1.23.11
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 3001
          name: web-ui
        resources:
          limits:
            cpu: 200m
            memory: 512Mi
          requests:
            cpu: 50m
            memory: 128Mi
        livenessProbe:
          tcpSocket:
            port: web-ui
          initialDelaySeconds: 60
          periodSeconds: 10
        readinessProbe:
          httpGet:
            scheme: HTTP
            path: /
            port: web-ui
          initialDelaySeconds: 30
          periodSeconds: 10
        volumeMounts:
        - name: data
          mountPath: /app/data
      volumes:
      - name: data
        persistentVolumeClaim:
          claimName: uptime-kuma-pvc

(Optional) I want to use SSL when accessing the web UI of Uptime Kuma, therefore I need to create a new TLS secret.

$ cat 5.tls-secret.yaml
apiVersion: v1
data:
  tls.crt: VERY-LONG-BASE-64-ENCODED-STRING
  tls.key: ANOTHER-LONG-BASE-64-ENCODED-STRING
kind: Secret
metadata:
  name: wildcard-tls-secret
  namespace: uptime-kuma
type: kubernetes.io/tls

The last file 6.ingress.yaml contains the manifest for ingress-nginx which allows me to access the Uptime Kuma at https://uptime.home-lab-internal-domain.com:

$ cat 6.ingress.yaml
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: uptime-kuma-ingress
  namespace: uptime-kuma
spec:
  ingressClassName: nginx
  tls:
  - hosts:
    - uptime.home-lab-internal-domain.com
    secretName: wildcard-tls-secret
  rules:
  - host: uptime.home-lab-internal-domain.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: uptime-kuma-svc
            port:
              number: 3001

References:

How to attach instance profile on EC2 with AWS CLI

Tue, 05 Mar 2024 18:08:15 +1100

This is a quick note to remind me on how to attach or associate an instance profile (IAM role) to an EC2 instance using AWS CLI. There is a bonus section at the end to show how to replace one IAM role with another one directly.

In this example, I already have a running EC2 instance i-0357ecc1111111111 running. I want to attach a new instance profile called SSMInstanceProfile to this instance. But as we all know, only one instance profile can be associated with an EC2 instance at one time. So, let’s check to see if our instance already has one attached:

Transform SSL cert to inline format

Tue, 27 Feb 2024 23:31:27 +1100

We all know that the content of SSL CRT and KEY is a long string of characters broken by new line characters. If we want to use those SSL .crt and .key files with Kubernetes as a TLS secret, they required to be encoded as base64 and be in one-line.

How to do this? Well, there are at least two ways. The first one is my favorite:

$ base64 -w0 drone.example.com.crt

LS0tLS1CRUdJTiBDRVJUSUXXX0FURS0tLS0tCk11SOQrekNDQXVPZ0F3SUJBZ0lVZW5BejFjb0ptakd4Q1dGVHRhOWVzeUM2WHZRd0RRWUpLb1pJaHZjTkFRRUwKQlFBd2dZUXhDekFKQmdOVkJBWVRBa0ZWTVJnd0ZnWURWUVFJREE5T1pYY2dVMjkxZEdnZ1YyRnNaWE14RHpBTgpCZ05WQkFjTUJsTjVaRzVsZVRFUk1BOEdBMVVFQ2d3SVUyRnV0eUJKYm1NeEV6QVJCZ05WQkFNTUNsTmhibmtnClUyVjJaVzR4SWpBZ0Jna3Foa2lHOXcwQkNRRVdFMjV2Y21Wd2JIbEFjMkZ1TjJsdVl5NWpiMjB3SGhjTk1qTXcKTmpFNE1ETTFOVFV4V2hjTk1qVXdPVEl3TURNMU5UVXhXakNCalRFTE1Ba0dBMVVFQmhNQ1FWVXhHREFXQmdOVgpCQWdNRDA1bGR5QlRiM1Yw
...

w0 : disable line wrapping

Another way is to use the good old tr command:

Set Alacritty default dimensions TOML version

Wed, 14 Feb 2024 16:48:10 +1100

I have previously posted a similar topic on how to set the default dimension for Alacritty at launch. However, recently, Alacritty switched to TOML for its configuration.

Here is the setting needs to be added to ~/.config/alacritty/alacritty.toml:

[window.dimensions]
columns = 133
lines = 40

Reference:

https://blog.khmersite.net/p/set-alacritty-default-dimensions/

How to restore a VM to its previous state XCP-ng

Thu, 04 Jan 2024 20:21:33 +1100

This evening while I was running the system update on one of the guest VMs running on my XCP-ng host, I accidentally rebooted the XCP-ng host. Why? Accident!

The guest VM is very important, it’s running Xen Orchestra for this XCP-ng server. Semi-fortunately, I remember I had a snapshot for this VM. The challenge for me was, how could I restore the VM using that previous snapshot without Xen Orchestra.

Using df command showing size in megabytes

Mon, 01 Jan 2024 11:50:12 +1100

Happy New Year 2024!

This is going to be a very short post on how to use ‘df’ command to display the disk space usage in megabytes. To display the output in MB (megabytes), we can use the -m flag with the df command as the following:

❯ df -m
Filesystem                 1M-blocks  Used Available Use% Mounted on
devtmpfs                           4     0         4   0% /dev
tmpfs                            852     0       852   0% /dev/shm
tmpfs                            341     6       336   2% /run
/dev/mapper/almalinux-root      7578  2068      5511  28% /
/dev/vda2                       1014   280       735  28% /boot
/dev/vda1                        599     8       592   2% /boot/efi
tmpfs                            171     0       171   0% /run/user/1000

It’s simple, isn’t it?

FreeBSD 14 shared object libssl.so.111 not found

Sat, 02 Dec 2023 20:32:28 +1100

FreeBSD 14.0-RELEASE just got relesed at the end of last month, and I wanted to upgrade my NAS server running FreeBSD 13.x-RELEASE to 14.0.

Using the installation instruction from [1], I was able to upgrade smoothly without any issues. Here are the steps:

# freebsd-update fetch
# freebsd-update install

# freebsd-update upgrade -r 14.0-RELEASE
# freebsd-update install

Reboot:

# reboot

After rebooting, freebsd-update(8)[2] needs to be run again to install the new userland components:

Upgrading RHEL 8 to RHEL 9 on AWS

Wed, 22 Nov 2023 23:16:05 +1100

So I have an EC2 instance running RHEL 8.9 which was recently upgraded from RHEL 7.9. Now, I want to upgrade it all the way to RHEL 9. Here is the worklog which recording the steps I performed to achieve that goal.

Step 0, perform a snapshot of the root volume of the instance, or create an AMI from it. In my case, this is just a test instance, so I skip taking the snapshot.

Install EPEL repository on RHEL 9

Wed, 22 Nov 2023 22:47:27 +1100

This evening I’m trying to enable EPEL repository on a RHEL 9 server, by following instruction is taken from How to install EPEL on RHEL and CentOS Stream article [1] by Red Hat Enable Sysadmin.

Enable the CodeReady Linux Builder repository.

$ sudo subscription-manager repos --enable \
    codeready-builder-for-rhel-9-$(arch)-rpms

Repository 'codeready-builder-for-rhel-9-x86_64-rpms' is enabled for this system.

Install the EPEL RPM.

$ sudo dnf install \
https://dl.fedoraproject.org/pub/epel/epel-release-latest-9.noarch.rpm

...snip...

Installed:
  epel-release-9-7.el9.noarch

Complete!

Let’s try to install htop (available from the EPEL repo) to verify that everything is working:

$ sudo dnf install htop -y
...snip...

$ rpm -q htop
htop-3.2.2-1.el9.x86_64

That’s it!

Find least common multiple (lcm) with Julia

Sun, 19 Nov 2023 23:17:13 +1100

One joy of being parents when your children are in higher grade (say year 4 or 5) is that you’ll get a chance to review math lesson again in order to explain or help your children with their math problem. Nowadays, things are much easier for us parents due to unlimited of resources on the Internet.

Earlier this evening, after spending time learning with my grade 4 child about Least Common Multiple (LCM) [1], I wanted to know the quickest way to verify the answer when computing of some numbers. While there are many implementations of many programming language, I found one way to do this using Julia with its built-in function Base.lcm [2].

No support for RHEL with high availability in-place upgrade

Wed, 15 Nov 2023 23:06:42 +1100

Well, if you know you know, otherwise, you could have wasted the whole evening trying to upgrade RHEL 7.9 with High Availability to RHEL 8.x, and failed!

If you read this post, head to the link at [1] and you’d see that Red Hat does not support i-place upgrades or rolling-upgrades of cluster nodes from one major release of RHEL to another. Here is an extract from [1]:

Red Hat does not support in-place upgrades or rolling-upgrades of cluster nodes from one major release of RHEL to another. For example, there is no supported method for updating some nodes in a cluster from RHEL 6 to RHEL 7, introducing them into the cluster with existing RHEL 6 nodes to take over resources from them, and then updating the remaining RHEL 6 nodes. Upgrades in major releases of RHEL must be done by migrating services from a running cluster on the old release to another cluster running the new release.

Here Documents

Fri, 10 Nov 2023 12:07:37 +1100

So, what’s “Here Docs”? Well, if you don’t know what it is yet, then hopefully by the time you finish reading this post you’ll know what it is.

Here docs or here documents is a special block code, of which we can use a form of I/O redirection to feed a command list to an interactive program, e.g. cat or the ex text editor according to [1].

Here is an example where a file basic-ingress.yaml was created using here docs.

Deleting old LVM devices file PVID last seen not found

Thu, 26 Oct 2023 23:50:45 +1100

On one of my servers, I used to have a storage device, /dev/sdb, attached to it. That storage was used as an LVM physical volume. It has later been removed, and now I just noticed the following message:

[root@banan ~]# lvs
  Devices file PVID CuDRE3nMN5FMNqYLViHrnE1D7OFDlbX6 last seen on /dev/sdb not found.
  LV         VG        Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  root       almalinux -wi-ao---- <28.40g
  swap       almalinux -wi-ao----   2.01g

Based some research found online, there could be outdated device entries in the device files located in /etc/lvm/devices/system.devices.

Rustup - update and remove Rust toolchain

Thu, 19 Oct 2023 21:13:20 +1100

rustup is a utility used to install and remove rust toolchain.

To list the current installed toolchain run:

kenno@c2:~$ rustup show
Default host: aarch64-unknown-linux-gnu
rustup home:  /home/kenno/.rustup

installed toolchains
--------------------

stable-aarch64-unknown-linux-gnu (default)
1.70.0-aarch64-unknown-linux-gnu
1.71.1-aarch64-unknown-linux-gnu
1.72.0-aarch64-unknown-linux-gnu

active toolchain
----------------

stable-aarch64-unknown-linux-gnu (default)
rustc 1.72.0 (5680fa18f 2023-08-23)

To remove a specific version of the toolchain, e.g. 1.70.0-aarch64-unknown-linux-gnu run:

kenno@c2:~$ rustup toolchain remove 1.70.0-aarch64-unknown-linux-gnu
info: uninstalling toolchain '1.70.0-aarch64-unknown-linux-gnu'
info: toolchain '1.70.0-aarch64-unknown-linux-gnu' uninstalled

Let’s verify:

kenno@c2:~$ rustup show
Default host: aarch64-unknown-linux-gnu
rustup home:  /home/kenno/.rustup

installed toolchains
--------------------

stable-aarch64-unknown-linux-gnu (default)
1.71.1-aarch64-unknown-linux-gnu
1.72.0-aarch64-unknown-linux-gnu

active toolchain
----------------

stable-aarch64-unknown-linux-gnu (default)
rustc 1.72.0 (5680fa18f 2023-08-23)

To install udpate the new toolchain, run:

Array in Bash

Wed, 18 Oct 2023 23:12:59 +1100

I have written a hand full of Bash scripts, but none of those utilized array. Why? It’s because of two main things: 1. I don’t know how to use array in Bash, and 2. I would normally switch to write the script in Python instead.

Today, however, I need to update an existing script written in Bash to make use of array. This was a perfect excuse for me to spend some 30 minutes to learn about array in Bash. I found a very good tutorial at the following [1].

Install Guest Tools on XCP-ng

Mon, 16 Oct 2023 20:08:36 +1100

On AlmaLinux, the guest-tool for XCP-ng is provided by a package named xe-guest-utilities-latest, which in turn is available from the epel-release repository.

The following list a few steps to get XCP-ng guest-tool installed on a VM running AlmaLinux 9.

Enable epel-release repository if not yet enabled by first installing a package called epel-release. In my case, the repo has been already enabled.

[root@xoa1 ~]# rpm -q epel-release
epel-release-9-7.el9.noarch

Install the guest-tool. If you’re unable to remember the full name of the package, just search for xe-guest.

[root@xoa1 ~]# dnf search xe-guest
Last metadata expiration check: 3:41:49 ago on Mon 16 Oct 2023 16:34:47.
=================== Name Matched: xe-guest ==================================
xe-guest-utilities-latest.x86_64 : XAPI Virtual Machine Monitoring Scripts

[root@xoa1 ~]# dnf install xe-guest-utilities-latest -y
...
Installed:
  xe-guest-utilities-latest-7.30.0-7.el9.x86_64

[root@xoa1 ~]# rpm -q xe-guest-utilities-latest
xe-guest-utilities-latest-7.30.0-7.el9.x86_64

Finally, enable and start the xe-linux-distribution service.

[root@xoa1 ~]# systemctl enable --now xe-linux-distribution.service
Created symlink /etc/systemd/system/multi-user.target.wants/xe-linux-distribution.service → /usr/lib/systemd/system/xe-linux-distribution.service.

[root@xoa1 ~]# systemctl status xe-linux-distribution.service
● xe-linux-distribution.service - Linux Guest Agent
     Loaded: loaded (/usr/lib/systemd/system/xe-linux-distribution.service; enabled; preset: disabled)
     Active: active (running) since Mon 2023-10-16 20:20:11 AEDT; 12s ago
    Process: 1714 ExecStartPre=/usr/sbin/sysctl net.ipv4.conf.all.arp_notify=1 (code=exited, status=0/SUCCESS)
    Process: 1715 ExecStartPre=/usr/sbin/xe-linux-distribution /var/cache/xe-linux-distribution (code=exited, status=0/SUCCESS)
   Main PID: 1720 (xe-daemon)
      Tasks: 9 (limit: 23054)
     Memory: 7.1M
        CPU: 42ms
     CGroup: /system.slice/xe-linux-distribution.service
             ├─1720 /usr/sbin/xe-daemon
             └─1723 logger -t xe-daemon -p debug

Oct 16 20:20:11 xoa1 systemd[1]: Starting Linux Guest Agent...
Oct 16 20:20:11 xoa1 sysctl[1714]: net.ipv4.conf.all.arp_notify = 1
Oct 16 20:20:11 xoa1 systemd[1]: Started Linux Guest Agent.

The guest-tool for XCP-ng has now been installed on a VM running AlmaLinux (9).

What is in a Longhorn volume?

Sun, 15 Oct 2023 18:57:07 +1100

Do you know? Well, before today, neither did I.

I’m pretty late to Kubernetes. I heard about it many hears ago, but unfortunately, I had no need to use it at home or at work. Even today, there is no workload that requires a Kubernetes cluster to run on. However, I think I can’t ignore Kubernetes any longer, and I need to learn about it now, well “better be late than never”, right?

warning: TERM environment variable set to 'tmux-256color'

Thu, 12 Oct 2023 19:02:02 +1100

I use ’tmux’ on anything that runs it, from FreeBSD, macOS and Linux.

On some of my Linux servers, noticeably openSUSE ones, when I connect to them via SSH, I would receive the following warning:

...
Have a lot of fun...
warning: Could not set up terminal.
warning: TERM environment variable set to 'tmux-256color'.
warning: Check that this terminal type is supported on this system.
warning: Using fallback terminal type 'ansi'.

What worse is that, when I switch to root account, the backspace key doesn’t work correctly. For example, hitting backspace will produce a space instead.

Grow partition with growpart

Fri, 06 Oct 2023 21:35:30 +1100

During the upgrade of Fedora 38 to Fedora 39 (beta) on my main desktop, the first attempt failed due to insufficient free disk space on the root volume. After some manual intervention such as vacuuming the journald logs, I was able to perform the successful upgrade. Not that it matters, but I’m writing this blog post on the same desktop running Fedora 39 Beta.

This post is to record how I increase the root volume on my desktop with the help of a few tools such as growpart, lsblk, resize2fs,…etc. Like always, if you stumble on this post and want to follow along, please do not just copy and pate the commands from here and run on your system. Try to understand what each command does, if you don’t, then you definitely must not copy and pate these commands!

How to delete Lightsail resources using AWS CLI

Thu, 05 Oct 2023 23:59:44 +1100

In this post, I’ll document how to use AWS CLI to delete a few Lightsail resources. I have never done this before, so this would be a good exercise for me. To make it less boring, I’m writing this post while I’m deleting these resources.

First step, I need to look for the instance name [1].

❯ aws lightsail get-instances --query 'instances[].name'
[
    "WordPress-1"
]

The above output is the name of the instance I’d like to delete. With its name, the instance can be deleted using the following command line [2]:

How to delete Memcached cluster using AWS CLI

Fri, 29 Sep 2023 20:41:14 +1000

If you have an ElastiCache Memcached cluster that you no longer need, it’s better to delete it. Dno’t believe me? Even AWS said so too:

It is almost always a good idea to delete clusters that you are not actively using. Until a cluster’s status is deleted, you continue to incur charges for it. [1]

Well, I have a Memcached cluster that I don’t need anymore. But instead of deleting this cluster using AWS console [1], I’m going to do this via AWS CLI.

Deleting VPC Endpoints With AWS CLI

Wed, 27 Sep 2023 22:45:41 +1000

This is a quick note on how to delete VPC endpoints that are no longer needed with AWS CLI.

First, we need to find all the vpc-endpoints-ids [1].

❯ aws ec2 describe-vpc-endpoints --query 'VpcEndpoints[].VpcEndpointId'
[
    "vpce-097008f8d26caxxxx",
    "vpce-07aaeabdefd8xxxx",
    "vpce-0bc6d548ff2e0xxxx"
]

Note: I replaced the last 4 digit with ‘xxxx’. It’s a good idea to try out without really deleting the VPC endpoints by supplying --dry-run to the command below:

❯ aws ec2 delete-vpc-endpoints --vpc-endpoint-ids vpce-097008f8d26caxxxx vpce-07aaeabdefd8xxxx vpce-0bc6d548ff2e0xxxx --dry-run

An error occurred (DryRunOperation) when calling the DeleteVpcEndpoints operation: Request would have succeeded, but DryRun flag is set.

Let’s delete all of the 3 resources:

How to extract a zip archive with Python on Windows

Tue, 26 Sep 2023 23:52:38 +1000

Have you ever been asked or wonder how to learning a programming language? If not, then you can skip this blog post. :-)

At work, a coworker said to me “I want to learn a programming language. Where do I start or how do I even start it?” I was asked this question because I had explicitly expressed my interest to my teams that I like programming a lot, though programming is not being used my professional career at the moment.

Installing Ingress-Nginx Controller with Helm

Tue, 26 Sep 2023 22:35:22 +1000

In my previous post, I showed how to install helm CLI on a server/instance running AlmaLinux 9. Now, I will share how to use helm to install the Ingress-Nginx Controller for a Kubernetes cluster.

We install a package known as “chart” from a Helm repository. Initially, there is no repo, and can be seen below:

$ helm repo list
Error: no repositories to show

In order to install Ingress-Nginx Controller, I first need to add a new repository.

Installing HELM Cli on AlmaLinux 9

Tue, 26 Sep 2023 21:01:05 +1000

Recently, I decided to pick up learning Kubernetes again after completely being absent from this world for many years. In this post, I’ll document how to install Helm CLI on AlmaLinx 9. Helm is like a package manager for Kubernetes. Helm CLI can be installed on your local machine, it does not to be installed on the Kubenetes node. However, in order to interact with your Kubernetes cluster, you’ll need to also have kubectl command as well as properly configured it to interact with your Kubernetes cluster.

How to restart KDE Plasma without logging out

Sun, 24 Sep 2023 22:46:10 +1000

I’m running KDE Plasma Version 5.27.8 on Fedora 38. It’s been very stable and Plasma crashes a lot less comparing to the old day when running Plasma 5.0 on (older) Kubuntu.

Anyway, today, my Plasma’s taskbar froze and I needed to restarted. Instead of logging out and logging back in, I found a way to restart the Plasmashell. Here is the command which worked for me for this Plasma version:

IPv6 addr-gen-mode = default - But what is that default value?

Sun, 17 Sep 2023 19:01:19 +1000

On Fedora 38, the version of NetworkMnager is 1.42.8, and the “default” setting for ipv6.add-gen-mode is default. The possible value for ipv6.add-gen-mode is eui64, stable-privacy, default-or-eui64, and default.

This blog post is my attempt to understand a bit more about this IPv6 setting addr-gen-mode. On my workstation, the NetworkManager connection in use in this post is called br0. Here are are some commands to display the version number of NetworkManager and the (default) current setting of ipv6.addr-gen-mode:

Configure IPv6 for Proxmox Host via Slaac

Sat, 16 Sep 2023 01:21:05 +1000

The Proxmox server running at home only has an IPv4 statically assigned to it. Since I’ve been trying to get all my connected devices at home to get IPv6 assigned, I figured I should try with this Proxmox server next.

I’m running Proxmox VE 8.0.4, and it’s based on Debian 12 (bookwarm). The settings for its network interfaces are stored in /etc/network/interfaces:

root@pve:~# cat /etc/network/interfaces
auto lo
iface lo inet loopback

auto vmbr0
iface vmbr0 inet static
        address 192.168.1.8/24
        gateway 192.168.1.1
        bridge-ports enp2s0
        bridge-stp off
        bridge-fd 0

Here is the output of vmbr0 device:

Nginx Redirect One Path to Another

Thu, 14 Sep 2023 00:51:40 +1000

Nginx is probably my favorite web server up to this moment, and it runs and serves websites on all of my servers. I should say, I also like Apache web server too, but not as much as Nginx.

Today, I need to redirect from one url path to another. It took me a while to get it right, and I’d better write it down before it’s forgotten.

This is what I want: https://demo.example.com/login -> https//demo.example.com/demo/login.

How to configure IPv6 on FreeBSD via SLAAC

Fri, 08 Sep 2023 19:05:36 +1000

I recently got IPv6 running at home, with most devices including my iPhone happily get an IPv6 assigned. My NAS running FreeBSD13.2 currently only has an IPv4 assigned, so I’m going to configure IPv6 for it too.

I’m still new to IPv6. The way I have it setup on my router, running OPNsense, is to set the “Router Advertisements” to “Unmanaged” with DHCPv6 disabled. “Unmanaged” for SLAAC (A flag), and SLAAC stands for Stateless Address Autoconfiguration. In simple term, each client will pick its own IPv6 based on the route prefix advertised by the router. This is just a simplification, and you should not quote for me this.

How did I renew Red Hat Developer Subscription

Wed, 30 Aug 2023 22:52:16 +1000

If you’re reading this post, it’s quite likely that you’re fully aware that Red Hat provide a no-cost Red Hat Developer Subscription for individuals. With this subscript you can use it run RHEL for free. The subscription only lasts one year, and when it expires it can’t be renewed. You must re-register.

I have a test RHEL vm, but I hardly use. So today when I turned it on and logged into it, the following message came up when i tried to update the system:

Fix cc: error trying to exec 'cc1plus' on openSUSE Leap

Tue, 29 Aug 2023 23:07:48 +1000

It’s currently almost 23:15, and I’m already sleepy. Therefore, this is going to be a short note on how I fixed an minor but annoying issue nvim-treesiter (Neovim’s plugin) on openSUSE Leap (15.5).

The error message is or was as below:

nvim-treesitter[yaml]: Error during compilation
cc: error trying to exec 'cc1plus': execvp: No such file or directory
Press ENTER or type command to continue

I don’t code in C++ nowadays, but the error looks like the C or C++ compiler was missing. But first, let’s show the version of openSUSE running on this instance, I mean VM:

Installing AWS CLI on AlmaLinux

Sun, 20 Aug 2023 18:37:13 +1000

I already wrote a blog post on How to install AWS CLI on RockyLinux, where I shared how to leverage the RPM package from EPEL repository. So what do I need to create a post here?

Well, when I tried to use the same method to install the AWS CLI on an AlmaLinux 9.2, there was an issue with dependency. Here is what happened:

[kenno@wedev1 ~]$ sudo dnf install awscli
[sudo] password for kenno:
Last metadata expiration check: 0:05:08 ago on Sun 20 Aug 2023 18:35:23.
Error:
 Problem: conflicting requests
  - nothing provides python3.9dist(docutils) >= 0.10 needed by awscli-1.23.10-3.el9.noarch
(try to add '--skip-broken' to skip uninstallable packages or '--nobest' to use not only best candidate packages)

Good thing is, there are a few ways to install AWS CLI on Linux. I’ll be using the method described at official AWS document to install the CLI.

How to delete AWS Workspace with AWS CLI

Thu, 10 Aug 2023 17:28:05 +1000

When you are finished with a WorkSpace, you can delete it. You can also delete related resources. In this post, I’ll be using AWS CLI to delete a WorkSpace that is no longer needed.

To delete a WorkSpace using AWS CLI, we can use terminate-workspaces command [2]. But first, I’d need to find the workspace id.

➜ aws workspaces describe-workspaces --query 'Workspaces[].WorkspaceId' --output text
ws-9xm222222

Now that I got the WorkSpace id as ws-9xm222222, I can proceed to terminate this WorkSpace.

How to stop AWS Workspace with CLI

Wed, 09 Aug 2023 18:45:01 +1000

I need to stop a WorkSpace now and I don’t want to login to AWS WorkSpace console.

The following is the steps I’m literally taking to achieve this goal.

Find out the WorkSpace ID, assuming that my AWS CLI has been setup correctly.

❯ aws workspaces describe-workspaces
{
    "Workspaces": [
        {
            "WorkspaceId": "ws-9xm222222",
            "DirectoryId": "d-9767555555",
            "UserName": "kenno",
            "IpAddress": "172.xx.x.xx",
            "State": "AVAILABLE",
            "BundleId": "wsb-clj855555",
            "SubnetId": "subnet-0a4ae4b324a799999",
            "ComputerName": "A-2B99WV33TITAN",
            "WorkspaceProperties": {
                "RunningMode": "AUTO_STOP",
                "RunningModeAutoStopTimeoutInMinutes": 60,
                "RootVolumeSizeGib": 80,
                "UserVolumeSizeGib": 50,
                "ComputeTypeName": "STANDARD",
                "Protocols": [
                    "PCOIP"
                ]
            },
            "ModificationStates": []
        }
    ]
}

We can see that the WorkSpace ‘ws-9xm222222’ is in AVAILABLE state. To stop this workspace now, run the following command:

❯ aws workspaces stop-workspaces --stop-workspace-requests WorkSpaceId=ws-9xm222222

Parameter validation failed:
Unknown parameter in StopWorkspaceRequests[0]: "WorkSpaceId", must be one of: WorkspaceId

❯ aws workspaces stop-workspaces --stop-workspace-requests WorkspaceId=ws-9xm222222
{
    "FailedRequests": []
}

Notice that the CLI option is case sensitive, and I “deliberately” made a mistake with WorkSpaceId to demonstrate this. Hahaha.

How to delete one word backward in Vim

Tue, 08 Aug 2023 23:30:09 +1000

The following is a sample of text opening in vim/neovim with line numbers:

1 What would be the command to delete one word backwards? 2 I know we can use ‘db’ to delete backword, and it would work 3 as what I wanted if the cursor is on the last character.

Assuming that my cursor is under letter ‘a’ of the word ‘command’ in line 1, and I want to delete the whole word ‘command’. How could this be done?

Query Latest Debian 12 AMI Id Using AWS SSM Parameter Store

Sat, 05 Aug 2023 00:24:53 +1000

Debian publishes their releases of Amazon Machine Image (AMI) for bookworm at Debian bookworm on Amazon EC2 [1]. There, you can find the AMIs for various regions and two architecture amd64 and arm64.

Another way to search for AMI for Debian 12 (bookworm) is to use AWS CLI with describe-images. Here is an example on how to list the 3 most recent AMIs of Debian 12 (amd64 architecture), sorted by most recent to the oldest:

Installing Jellyfin Media Player on OpenSUSE Tumbleweed

Sat, 29 Jul 2023 10:28:07 +1000

As of today, Jellyfin Media Player is not available on (official?) repos for OpenSUSE Tumbleweed. To install it, I need to first add a repository, kind of like Fedora Copr, which provides this package.

$ sudo zypper addrepo https://download.opensuse.org/repositories/home:playablepliable/openSUSE_Tumbleweed/home:playablepliable.repo

[sudo] password for root:
Adding repository 'home:playablepliable (openSUSE_Tumbleweed)' ......................................[done]
Repository 'home:playablepliable (openSUSE_Tumbleweed)' successfully added

URI         : https://download.opensuse.org/repositories/home:/playablepliable/openSUSE_Tumbleweed/
Enabled     : Yes
GPG Check   : Yes
Autorefresh : No
Priority    : 99 (default priority)

Repository priorities are without effect. All enabled repositories share the same priority.

Once the repo was added, the jellyfin-media-player package should be available and can be installed using the following commands:

Connect to Wifi with nmcli

Sun, 23 Jul 2023 15:51:55 +1000

First check if the Wi-Fi device is enabled or not:

$ nmcli radio wifi

If the output shows that the Wi-Fi is disabled, then it can be enabled with:

$ nmcli radio wifi on

If we already know the access point, then skip the following step. Otherwise, to identify the access points, run:

$ nmcli dev wifi list

Supposed we want to connect to the access point named ’totoro’, and the password is ’t0t0r02023’, we can connect to it by running the following command:

Changing Permalink in Hugo

Sat, 15 Jul 2023 21:19:54 +1000

This post is related to the previous one about changing a theme in Hugo. After I changed the theme to “PaperMod”, I realized that each article or blog post is under ‘post/date’ URL path. For example, the following is the permanent link/path of a post:

https://blog.khmersite.net/post/2023/06/changing-hugo-theme/

Previously, there was no word post in the URL path, and I still want it gone again with this new theme, as below.

https://blog.khmersite.net/2023/06/changing-hugo-theme/

The problem is, I forgot how it was done!

Changing Hugo Theme

Tue, 20 Jun 2023 22:36:37 +1000

Had you visited this blog recently, you may have noticed that the blog’s theme has changed.

Here is a quick note on how I changed the theme of this blog from cayman-hugo-theme to PaperMod. For a little background, Hugo themes are installed as git submodule. Want a quick recap on how to use Git Submodule? Here is a good content [0].

First, the current theme needs to be removed:

$ git submodule
4a924cef54081b61530a30bd69d442ae99916561 themes/cayman-hugo-theme (heads/master)

$ git submodule deinit "themes/cayman-hugo-theme"
$ git rm "themes/cayman-hugo-theme"

$ git commit -m 'remove theme cayman-hugo-theme'

Add a new theme, PaperMod [2] as the submodule.

$ git submodule add --depth=1 https://github.com/adityatelange/hugo-PaperMod.git themes/PaperMod
$ git add .gitmodules
$ git add config.yml

$ git commit -m 'change theme to PaperMod'
$ git push

Note: As each Hugo theme contains specific parameters, I also had to update the config.yml required by this new theme. A copy of a sample config.yml is available at the theme’s exampleSite [1].

How to find EC2 instance ID from a known private IP using AWS CLI

Fri, 26 May 2023 16:50:45 +1000

When I first started to use AWS CLI, I felt overwhelmed, and I wondered how long it would take me to be familiar with the tool. Fast forward to many months later, I find the AWS CLI very pleasant to use. For example, there are same patterns and the CLI reference page online is quite useful.

Anyway, like many thing I’ve learned about Linux, I learned and could retain the information better with practice and document. So, I’m gonna just dump the commands that I need and learn here to help my future self should I need to find the same commands.

How to Zip a file using command line

Mon, 22 May 2023 19:10:22 +1000

I normally use gzip for file compression. However, there is time when you want to share a compressed file with Windows users and you want to avoid them cursing at you. One good solution is to use zip compression (even if I had to learn how to do it on a Linux machine).

Well, like always we can run man zip to learn more about it, but since you’re reading this, it is unlikely that you’re doing that. So, here is how you can do it.

Proxmox Cannot Stop VM - Help!

Tue, 25 Apr 2023 21:36:17 +1000

I’ve been running a few VMs on Proxmox, including a Pfsense VM, for over a year without a single issue. This evening, however, I noticed that I wasn’t able to access any local DNS records due to the VM hosting DNS server was not responding.

On checking the Proxmox console, I could see that that VM with ID 102 was definitely not responding. So, I tried to reboot, stop and even reset. None of which worked. Knowing that Proxmox is based on or using KVM, I guess there must be many commands that can be run directly on the Proxmox host itself.

How to Run Redis in Podman Container

Wed, 22 Feb 2023 23:30:49 +1100

This is just a quick note on how to run Redis as a container using Podman on Ubuntu 22.04 (i.e. there will be no mention about SELinux.)

Create a persistent volume for the Redis container

I like storing all data/volume for containers under /srv/data. So I’ll create a sub-directory called redis-data under the same location.

# mkdir -p /srv/data/redis-data

Pull the Redis image

# podman pull docker.io/redis

Create and run the Redis container

# podman run -d --name redis_server \
    -v /srv/data/redis-data:/var/redis/data \
    -p 6379:6379 redis

Create systemd service for the Redis container

I like creating a systemd service to enable/start the container.

Installing Htop on Oracle Linux 8

Mon, 06 Feb 2023 22:51:36 +1100

I want to install htop on Oracle Linux 8.7. How hard could it be?

TL;DR; - it’s not hard, but it took me a little while to get htop installed. I’m not new to (most) Linux distros, but this is the first time I’m using Oracle Linux.

So, let’s start by showing some basic information.

[root@catbus ~]# cat /etc/os-release | grep -i pretty
PRETTY_NAME="Oracle Linux Server 8.7"

[root@catbus ~]# rpm -qi htop
package htop is not installed

[root@catbus ~]# dnf search htop
Last metadata expiration check: 0:23:03 ago on Mon 06 Feb 2023 11:32:58 AM GMT.
No matches found.

The above output shows that htop is not installed, and the package is not available in all enabled repositories.

How to Install AWS CLI on RockyLinux

Tue, 31 Jan 2023 12:02:59 +1100

The awscli package is available from the EPEL repository, which is not enabled by default on RockyLinux.

Enable the EPEL repo by installing epel-release pacakge.

$ sudo dnf install epel-release

Once the EPEL repo is successfully enabled, we can install awscli package.

$ sudo dnf install awscli

Enable and verify that the awscli is installed on the system.

$ aws --version
aws-cli/1.18.156 Python/3.6.8 Linux/4.18.0-425.10.1.el8_7.x86_64 botocore/1.18.15

As a bonus, here is how to configure the AWS credential.

Check disk usage on root (/) partition excluding other partitions

Thu, 22 Sep 2022 11:29:53 +1000

While checking the root partition on my desktop today, I noticed that its usage is at 89% with just 6GiB free. For this reason, I wanted to find out what’s consuming most spaces and whether I can clean it up a bit.

# df -h /
Filesystem                       Size  Used Avail Use% Mounted on
/dev/mapper/fedora_watamem-root   56G   47G  6.3G  89% /

The first two commands that come to my mind are du and ncdu. In this post, I’ll use ncdu to investigate the disk usages on the ‘/’ partitions.

How to add additional remote git repository

Sat, 03 Sep 2022 12:24:10 +1000

Though it’s not very common in my daily work, I occasionally need to add additional remote Git repositories mainly for pushing. In fact, I did this about 4 to 5 times already, and thought that it’d be the last time.

Today, I need do this again, and I forgot!

Currently, I have the following remote repository set for ‘origin’:

❯ git remote -v
origin  git@git.homeserver.local:kenno/ansible.git (fetch)
origin  git@git.homeserver.local:kenno/ansible.git (push)

I wanted to add https://kenno@gitea.homeserver.local/kenno/ansible.git as the additional repo for pushing.

How to reset Rhythmbox library

Fri, 02 Sep 2022 20:53:10 +1000

Rhythmbox stores its music database as an XML file located in ~/.local/share/rhythmbox/rhythmdb.xml. The easiest way to reset this database is to close the Rhythmbox program, and completely remove the rhythmdb.xml file.

➜ pkill rhythmbox
➜ rm ~/.local/share/rhythmbox/rhythmdb.xml

➜ rhythmbox &

Reference:

How does one clear the Rhythmbox music library database?

How to check cpu temp on Debian and Ubuntu

Mon, 29 Aug 2022 21:08:50 +1000

This is just a quick note for me to display CPU temperature on one of my fanless device which runs Debian.

Install the required package lm-sensors
Run the sensors command.

Here is a sample output:

root@pve:~# sensors
coretemp-isa-0000
Adapter: ISA adapter
Package id 0:  +45.0°C  (high = +105.0°C, crit = +105.0°C)
Core 0:        +37.0°C  (high = +105.0°C, crit = +105.0°C)
Core 1:        +37.0°C  (high = +105.0°C, crit = +105.0°C)
Core 2:        +37.0°C  (high = +105.0°C, crit = +105.0°C)
Core 3:        +37.0°C  (high = +105.0°C, crit = +105.0°C)

acpitz-acpi-0
Adapter: ACPI interface
temp1:        +27.8°C  (crit = +119.0°C)

Reference:

How to upgrade FreeBSD from 13.0 to 13.1

Tue, 19 Jul 2022 10:51:46 +1000

I feel upgrading FreeBSD from 13.0 to 13.1 is so minor that it might not worth a blog post. The thing is, I just did this upgrade on one of my 2 nas servers a month ago, and now I forgot how to do this already.

This post should be short, and I will include the reference(s) at the end if you’d like to learn more about this update process.

How to Deploy Xen Orchestra Appliance on XCP-ng

Sun, 10 Jul 2022 14:34:13 +1000

This is a quick note on how I got the Xen Orchestra Appliance (XOA) on a new XCP-ng server. I know there are many guides out there, and in fact this is not my original content, but I want to capture what I did to get it working.

Here are the steps I performed on my server in order to install XOA:

[14:16 xcpng ~]# bash -c "$(curl -sS http://xoa.io/deploy)"

Welcome to the XOA auto-deploy script!

Network settings:
IP address? [dhcp]

Your XOA will be started using DHCP

xoa SSH account:
Password? (disabled if empty)

xoa account is disabled, to enable it later see https://xen-orchestra.com/docs/troubleshooting.html#set-or-recover-xoa-vm-password

Importing XOA VM...
Booting XOA VM...
Waiting for your XOA to be ready…

Your XOA is ready at
  https://192.168.1.207/

Default UI credentials: admin@admin.net/admin

VM UUID: 19e56589-ed0d-5a24-c845-75b40b344f3b

[14:24 xcpng ~]#

Next, login to the XOA at https://192.168.1.207 using the default credential to connect the XCP-ng server this:

Restoring Postgresql DB backup with different owner role

Sun, 03 Jul 2022 23:20:48 +1000

Like the title says, when restoring a Postgresql database onto a different server which happens to have a dfferent role owner, extra care is needed, otherwise similar error message below will come up:

pg_restore: from TOC entry 217; 1259 17163 TABLE users_collections webdev1
pg_restore: error: could not execute query: ERROR:  role "webdev1" does not exist
Command was: ALTER TABLE public.users_collections OWNER TO webdev1;

pg_restore: from TOC entry 218; 1259 17168 TABLE users_organizations webdev1
pg_restore: error: could not execute query: ERROR:  role "webdev1" does not exist
Command was: ALTER TABLE public.users_organizations OWNER TO webdev1;

pg_restore: warning: errors ignored on restore: 19

What happened was that there was no role named webdev1 on the Postgreseql server where the database restoring was performed. Instead, on my database server, I had a role named webdev2.

Mounting NFS share with Systemd Automount

Mon, 13 Jun 2022 22:41:28 +1000

On my main workstation running Fedora 36, I use both autofs and Systemd automount to mount NFS on demand. Gradually, I’m leaning toward just to use Systemd automount.

Here is just a brain dump with an example of mounting an NFS share with Systemd autmount. Though, I had done this before, I found this blog post, available at [1], provides details on how to do this.

Assumption

The NFS server and share: banan.example.com:/srv/music
The preferred local mount point: /srv/banan/music

Create required Systemd unit files

We will need 2 unit files: the mount unit and the automount unit.

How to Enable Proxmox Guest Agent

Sun, 12 Jun 2022 19:16:47 +1000

I recently had a need to run Proxmox Virtual Environment (7.2-4) at home for a project. So far everything seemed to be straight forward, partially thanks to KVM technology used in Promox.

However, I also learned a few things along the way too. The first thing that I had look up on the Internet to get it working is to activate (Promox) qemu-guest-agent.

If you’re reading this, it’s likely you didn’t get it working on first trial either.

Start and Stop Network Service on FreeBSD

Sun, 05 Jun 2022 21:09:31 +1000

A quick note for me to remind myself how to stop/start network service on FreeBSD (13.0).

To stop or start, run one of the following commands:

# service netif stop
# service netif start

To restart, just replace stop or start with restart:

# service netif restart

I also just found out that the above commands will nto restarting the routing service, as they only stop/start/restart network.

To restart the routing service on FreeBSD, run:

How to delete disk partitions on Windows using PowerShell

Sun, 15 May 2022 18:43:47 +1000

Today I just added an old SSD to a Windows machine to use it as a back up drive. With old disks, usually they come with existing data, and I wanted to get rid of it. The problem is I couldn’t figure out how to do this using the Disk Management, the native GUI application used to manage disks.

The problem could be simple to Windows users. Basically, when I right-clicked on the 2 partitions (450 MB and 100 MB) on Disk 0, there is no option to remove them.

Turn on bluetooth on login screen in Tumbleweed

Sun, 10 Apr 2022 21:01:40 +1000

After taking a very long break (over a decade) from running openSUSE on my person machine, I finally got Tumbleweed installed on a spare Intel NUC machine. If you’re one of my blog readers, expect to see more contents about SUSE/openSUSE later.

Today, I’m going to share how I fix the issue with bluetooth keyboard/mouse not connected to this NUC at the login screen. I can’t remember I needed to do that my main machine running Fedora, but oh well, the fix is simple enough (if you know now).

How to Create Exfat Filesystem on Usb

Thu, 31 Mar 2022 17:33:15 +1100

I have a UBS drive formatted as fat32 because I need to share it with Linux and macOS. When I want to copy a Linux ISO file which is larger than 4GiB, this was not possible due to the limitation of fat32 filesystem.

A solution is to format that USB drive with exfat filesystem. I will do this on a Fedora 35 machine, but the process should be familiar for other Linux distros too.

Create a Disk Image With dd Command

Sat, 19 Mar 2022 21:00:58 +1100

Situation:

I want to re-use an external drive which already contains some data. So I will create a disk image on an external drive in case I need to copy that image back to the drive in the future.

Solution:

Normally, I just run dd to create an file.img when the disk is small, e.g. SD card. However, the drive capacity is 512GB. So a better option is to compress the image. Here is how this can be done:

mkfs.xfs: cannot open /dev/sda1: Device or resource busy

Sun, 13 Mar 2022 20:10:03 +1100

I’m trying to create an XFS filestem on a used disk, and got into a problem. Here is the error message:

# mkfs.xfs /dev/sda1
mkfs.xfs: cannot open /dev/sda1: Device or resource busy

So, let’s see if I can fix it. (Spoiler alert: I think I can, even though it’s not yet done at the time of this writing.)

Let’s check the partitions of /dev/sda:

# parted /dev/sda print
Model: ATA ST1000LM014-1EJ1 (scsi)
Disk /dev/sda: 1000GB
Sector size (logical/physical): 512B/4096B
Partition Table: gpt
Disk Flags:

Number  Start   End    Size   File system  Name  Flags
 1      1049kB  512GB  512GB  ntfs         1

So, there is a partition (/dev/sda1) with 512GB in size, and its filesystem is ntfs. I was pretty sure that I had selected xfs as the filesystem.

Using xclip to copy terminal content to clipboard

Fri, 04 Mar 2022 23:25:11 +1100

It’s quite annoying when I know the command I can use to copy the content on a terminal to clipboard. I know, I can run man xclip, but I think it’s still easier for me to visit this page and see how to do it.

For example, I want to copy the content of my ssh keypair, ed2559.pub, to clipboard, and here how it can be done:

➜ xclip -sel clip < ~/.ssh/id_ed25519.pub

Or:

LVM - How to Activate or Deactivate a Volume Group

Thu, 03 Feb 2022 22:50:10 +1100

Well, I hardly need to activate or deactivate LVM volume groups. But when I do, I also hardly remember the command required to do that. So hopefully, I can refer to this post should I need to perform one of these tasks in the future.

Since a volume group is activated by default when it is created, let’s start with a command to deactivate it.

# vgchange -a n example_volume_group

Like wise, to activate a volume group, use the following command:

FreeIPA reset failed locked out admin account

Thu, 03 Feb 2022 00:06:21 +1100

This is a short note on how to unlock admin account for FreeIPA.

# kinit admin
kinit: Client’s credentials have been revoked while getting initial credentials

When too many incorrect password attempts are made, the admin account is locked out. To unlock it, perform the following on the FreeIPA server:

# ldapmodify -x -D "cn=directory manager" -W
Enter LDAP Password:
dn: uid=admin,cn=users,cn=accounts,dc=example,dc=com
changetype: modify
delete: krbLoginFailedCount

To process the modification enter Control-D. If it’s successful you’ll receive a this message:

Freeipa Unable to Communicate With Cms 403

Wed, 02 Feb 2022 23:48:51 +1100

A new post, a new problem, and a solution.

Earlier today I worked on a task involving SSSD, System Security Services Daemon, a system service to access remote directories and authentication mechanisms. It got both excited and a little worried at the same times, since it’s been a long while since I had do anything with SSSD.

Fast forward to the evening, I realized I had a FreeIPA server set up a long time ago right after passing the Red Hat Certified Specialist in Identity Management exam (EX362). Note this FreeIPA server was actually a second server I had set up after the EX362 exam. The original server was based on CentOS 7. The problem

Foreman: Create a new product & repository for AlmaLinux

Sun, 30 Jan 2022 13:07:42 +1100

A few days ago I started to re-surrect my Foreman(/katello) server and wanted to use it to pull content from remote repository for AlmaLinux. This involves updating Foreman with a new product and related AlmaLinux repository. I wrote a similar post on creating product & repository using hammer before for EPEL 8. However, it’s been a long while and things could change with the current version of Foreman server.

# rpm -qa | egrep -i '^foreman-[0-9]|^katello-[0-9]|^pulp-server-[0-9]'
katello-4.3.0-1.el8.noarch
foreman-3.1.1-1.el8.noarch

# hammer --version
hammer (3.1.0)
 * hammer_cli_foreman (3.1.0)
 * hammer_cli_foreman_remote_execution (unknown version)
 * hammer_cli_foreman_tasks (unknown version)
 * hammer_cli_katello (1.3.1)

There would be 3 steps:

Resizing KVM qcow2 Image

Sat, 25 Dec 2021 08:05:07 +1100

I’m quite sure I’d resized qcow2 images before. However, when I needed to resize an image today for my VM at home, I totally forgot about it. Well, this means it’s a good excuse for me to just write down a few commands to help me in the future.

If you try to follow a long, two things you wanna keep in in mind: do it at your own risk, and always backup your data before you make change to it. Having said, that’s get started.

bash: append_path: command not found

Thu, 09 Dec 2021 21:52:12 +1100

I have a few Raspberry Pi at home, they’re used for specific purposes such as Kodi media player, Pi-hole server, and a backup DNS/DHCP server. Recently, I need to turn on the backup DNS/DHCP server, which is one of the Raspberry Pi devices running Arch Linux.

When I logged into to the server, I saw a message complaining that bash: append_path: command not found. It’s been so long since this little server, so I can’t remember what happened last time.

Set default window's dimensions for Alacritty

Wed, 17 Nov 2021 20:52:25 +1100

I haven’t really posted anything new recently as I’ve just had a big transision in my career. I may or may not write about this in the future, as I don’t think it’s that relevant to you.

Anyway, I’ve been having this trouble with window size of Alacritty being too small on launched.First what is Alacritty? It’s an terminal emulator written in Rust. It also makes use of GPU-acceleration, which should improve some performance in theory. I tried to make change to the config file of Alacritty, and it didn’t seem to work so I wasn’t sure I made the right change.

Configure Interface Teaming Using Nmcli

Tue, 31 Aug 2021 23:29:27 +1000

If you want to know what is Network Teaming, please check out this link.

In this post, I’m going to just list all the commands required to setup a team interface.

Let’s list the available network interfaces I have on my server.

$ nmcli dev status
DEVICE      TYPE      STATE                   CONNECTION 
enp1s0      ethernet  connected               enp1s0     
enp7s0      ethernet  connected               student    
virbr0      bridge    connected (externally)  virbr0     
enp8s0      ethernet  disconnected            --         
enp9s0      ethernet  disconnected            --         
lo          loopback  unmanaged               --         
virbr0-nic  tun       unmanaged               --

From the above output, you probably can guess that I’m going to use enp8s0 and enp9s0 to create a team network interface.

What does source (command) do?

Mon, 30 Aug 2021 18:22:39 +1000

If you’re a seasoned Linux user, you may have used source command once or twice before. You might also have used ., the exactly same command, instead. Both source and . are shell builtin commands.

I have used this many times, but I only used for one purpose which is to read the environment variables from a file to the current shell environment. So, when I was asked during a job interview, “What does source do?”, the only answer I could tell them was - I personally only use source command to read the variables into the current shell environment.

Dolphin Error "Could not enter folder tags:/"

Sat, 31 Jul 2021 10:41:22 +1000

I normally use dwm as the Windows manager on my laptop. However, I occationally need to switch to Plasma to test some applications out. This laptop is currently running Fedora 34 which has been upgraded from previous versions as old as 28, I believe.

When I run Dolphin, there is an annoying error message “Could ont enter folder tags:/”. Though it doesn’t cause any problems, it’s very annoying.

I found a solution from bug report #437176 suggesting to purge Baloo database. Here is the command to run:

Unable to Use tar to Decompress tar.bz2 File

Sun, 25 Jul 2021 17:18:43 +1000

I just setup a new server with a minimal installation of AlmaLinux 8. AlmaLinux is a variant of free Red Hat Enterprise Linux 8. It’s like a CentOS 8, but will have a full support until the end of RHEL 8 life cycle.

This server is to serve as a new proxy for all VMs inside my home lab. I want to use tinyproxy which is need to be compiled from source as the RPM package is not available as of the time writing. After downloading the source code, and try to decompress it, I was presented with the following error message:

List Block Devices on FreeBSD

Wed, 14 Jul 2021 15:00:03 +1000

Recently, I found out that the ZFS pool on a FreeBSD is running out of space. There is no option to clean up this storage, but there are spare disks. So the next logical thing to do is to add 2 extra disks to the existing (mirror) ZFS pool.

This FreeBSD server is a virtual machine (VM), and after attaching 2 physical disks to this VM, I had difficulty identifying these disks. Well, I could guess it, but this is a production server, and I really don’t want to spend my whole weekend to setup this server from the backup. :)

How to remove old kernels on Void linux

Sat, 10 Jul 2021 21:06:03 +1000

I have a Void linux VM which only gets turned on once in every month. Today, when I booted up and updated the packages on this VM, I noticed that there are many old kernels installed. As a seasonal Void user, I had no clue on how to remove older kernels.

Fortunately, a quick Google search pointed me to a video: VOID Linux: Removing old kernels with vkpurge. Basically, Void comes with a pre-installed utility program called vkpurge. (man vkpurge for more info.)

Check Exit Status Code for Kerberos Ticket Validity

Mon, 05 Jul 2021 15:53:12 +1000

If you’re familiar with Kerberos, one way to check if a ticket is valid is to run klist command.

❯ klist 
Ticket cache: FILE:/tmp/krb5cc_1001
Default principal: username@UNIVERSITY.EDU.AU

Valid starting     Expires            Service principal
02/07/21 11:26:50  02/07/21 21:26:50  krbtgt/UNIVERSITY.EDU.AU@UNIVERSITY.EDU.AU
        renew until 03/07/21 11:26:50
02/07/21 12:24:07  02/07/21 21:26:50  cifs/server1.UNIVERSITY.edu.au@UNIVERSITY.EDU.AU
02/07/21 12:24:07  02/07/21 21:26:50  cifs/server1.UNIVERSITY.edu.au@UNIVERSITY.EDU.AU

❯ date
Mon 05 Jul 2021 16:01:59 AEST

From the above output, the principal ticket expired since 2 Jul. So how do we find out if the Kerberos (principal) ticket expires programmatically? This is something that I was trying to find out a few years ago, but kinda have been forgotten due to low priority.

How to Scan for IPs of Connected Devices

Sat, 03 Jul 2021 02:17:42 +1000

Suppose you just connect a Raspberry Pi to your home network using ethernet interface, and the Pi is not connected to a display device. How would you find an IP of that Raspberry Pi?

Well, you’re right…whatever you say. There are a few ways to do this - looking at DHCP log, router log, …etc. But here is an even easier way to achieve this - using a command line tool called nmap.

Service unavailable ERF64-6496 - There are migrations pending in the system.

Tue, 29 Jun 2021 20:53:35 +1000

I just updated my Foreman server and reboot, then this happened when I accessed the web console:

Service unavailable ERF64-6496 [Foreman::MaintenanceException]: There are migrations pending in the system.

This was the first time I’ve seen this message, and possibly because I haven’t done the update frequently enough. Fortunately, according to this blog post, it should be relatively easy to fix.

[root@foreman ~]# sudo foreman-rake db:migrate
API controllers newer than Apipie cache! Run apipie:cache rake task to regenerate cache.
== 20210525144427 EnforceUniqueTemplates: migrating ===========================
-- add_index(:templates, [:type, :name], {:unique=>true})
   -> 0.0232s
== 20210525144427 EnforceUniqueTemplates: migrated (0.0341s) ==================

== 20210610131920 RestrictSendmailLocation: migrating =========================
== 20210610131920 RestrictSendmailLocation: migrated (0.0016s) ================

[root@foreman ~]# sudo foreman-rake db:seed
API controllers newer than Apipie cache! Run apipie:cache rake task to regenerate cache.
User with login admin already exists, not seeding as admin.

As suggested, I also ran apipie:cache rake task to generate cache.

LVM Device Blah Excluded by Filter

Fri, 18 Jun 2021 18:11:44 +1000

If you use LVM frequently enough, especially when re-using existing disks, you might come a cross a problem when you’re unable to create a physical volume from that disk. For example, here is what I encountered today when I tried to create a physical volume on a device called /dev/sdb.

[root@db3 ~]# pvcreate /dev/sdb
  Device /dev/sdb excluded by a filter.

I’m sure I haven’t had any filters in /etc/lvm/lvm.conf.

Where is which in PowerShell

Wed, 16 Jun 2021 16:44:20 +1000

As the title says, an easy way to find out the path of a program/command on Windows using PowerShell can be done with Get-Command cmdlet.

For example, I want to find out where I had installed nvim (Neovim) on a rarely use Windows machine. To do this, I can execute the following command:

❯ Gt-Command nvim

CommandType     Name                                               Version    Source
-----------     ----                                               -------    ------
Application     nvim.exe                                           0.0.0.0    C:\Program Files\Neovim\bin\nvim.exe

With PowerShell, we can also just print a specific attribute (?) of an object.

How to Remove ZFS Meta Data on FreeBSD

Wed, 26 May 2021 23:02:42 +1000

It’s been quite a while since I last posted something here. It’s not that I haven’t come across many issues in tech, it’s just that I haven’t had enough time to write anything.

So I’m going to share how to easily clear the ZFS metadata on a disk previously used in a ZFS pool. Here is an example - I have an external drive, and it is detected as /dev/da0 when plugged into a FreeBSD server. Though I don’t remember having used it as a member of a ZFS pool called tank, the following output does show that it is the case:

Vim Replace String 256 with

Sun, 09 May 2021 13:24:54 +1000

What was your first text editor when you started using Linux/Unix? Mine was pico. It was very easy to get started with and quite similar to nano. Then I moved to emacs and sticked with it for a long while. Eventually, I’ve switched to vim (or neovim), and that’s what I have been using until now.

Well, the thing about text editor or may be this also applies to many other things, you’re only familiar with features that you constantly use. This means I only know a small subsets of what vim can do.

Enable a Repo the Ansible Way

Sat, 24 Apr 2021 22:50:37 +1000

Recently I need to install a package called Lmod on a Red Hat 8 server. Lmod is available from RHEL 8 EPEL8 repository, however it has a dependency called lua-filesystem which is only available from codeready-builder repository. On my RHEL 8 server, the codeready-builder repository is not enabled by default.

Here is how I’ve got Lmod installed manually:

# subscription-manager repos --enable codeready-builder-for-rhel-8-x86_64-rpms
# dnf install Lmod

Looking at the above commands, I needed to enable the codeready-builder-for-rhel-8-x86_64-rpms first before installing Lmod. The thing is, I’m going to forget that Lmod requires lua-filesystem which is not available from the same repository as Lmod unless I write it down somewhere. Or better yet, let’s automate it with Ansible!

Looping Through Line in a File in Bash

Sat, 17 Apr 2021 18:39:37 +1000

I wanted to install vim package on FreeBSD 13.0, and did so without realizing that there were over 86 additional dependency packages installed. This was done with pkg install -y vim command.

Anyway, I wanted to clean up by removing vim and those dependencies after all this is a headless server. Removing vim package doesn’t remove the installed dependencies.

Fortunately, I was able to copy and paste the names of dependency packages and save it to a file. My first thought was to just go through each line in that file and run pkg delete -y PACKAGE. In the past I needed to do similar thing in a bash script or command to loop through the content of a file per line. Guess what? I no longer remember how to do that. Hence I’m writing this post to remind my future self in case I need to do this similar thing again.

Labeling an exFAT Partition File System

Sat, 10 Apr 2021 23:13:18 +1000

I just formatted an external drive with exFAT file system with the intention to share this drive between Windows/Linux/macOS.

When the drive is mounted on my Fedora desktop, it shows as:

/dev/sde1 on /run/media/kenno/E17F-B2B1 type exfat ()(rw,nosuid,nodev,relati...)

I want to give it a name, so it’ll be mounted as: /run/media/kenno/DRIVE_NAME. On Linux system, we can use a tool called exfatlabel to get or set the exFAT file system. I already created a partition and format it (mkfs.exfat /dev/sde1) on /dev/sde1 partition.

Work Around for Dracut and LUKS Issue on Pre-release Fedora 34

Sat, 10 Apr 2021 00:57:12 +1000

I’ve been running Fedora 34 pre-release version even before it became beta. Everything has been working so far until recently when a package dracut was updated from 0.58 to 0.58-1. What is dracut? Good question. It’s an initramfs infrastructure used on Fedora system. Find out more from Dracut.

The issue that introduced in version 0.58-1 on F34 is that it prevents any machines that use LUKS encryption for root partition to boot. The issue has been reported here. As of today, there is not yet a fixed version of dracut for F34 yet.

Clean Up Systemd Journal Logs

Fri, 26 Mar 2021 19:15:29 +1100

On my Fedora 33 system, the systemd journal is persistently logged. Over time, the size of the log accumulate quite a lot.

# du -shx journal/
4.2G    journal/

I already cleaned up the log twice in the past, but I already forgot how to do it. To fix my short-term memory, I’m going to document how I do this by following this blog post Clear systemd journal.

The command for cleaning up old logs is journalctl with the option --vaccume-time=OLDER_THAN_TIME. To read more about this, we can check the journactl manual page. (man journalctl and search for vacuume key word.)

Create libvirt Virtual Network From an XML File

Mon, 22 Mar 2021 14:19:36 +1100

I have a need to setup a virtual network on a VM-host server. Usually, I just use the virt-manager gui application to create this task. However, I’d like to do this via command line this time. Why? Well, why not? It’s always fun to learn new thing. :)

libvirt keeps network configuration in XML files under /etc/libvirt/qemu/networks/. Here is what I have on one of my machines:

# ls -1 /etc/libvirt/qemu/networks/*xml
/etc/libvirt/qemu/networks/classroom.xml
/etc/libvirt/qemu/networks/default.xml
/etc/libvirt/qemu/networks/kubernetes.xml
/etc/libvirt/qemu/networks/minikube-net.xml
/etc/libvirt/qemu/networks/other.xml
/etc/libvirt/qemu/networks/storage.xml
/etc/libvirt/qemu/networks/student.xml

We can use also list all the available libvirt-related virtual networks using virsh command:

Passed EX403 Satellite 6 Administration

Tue, 09 Mar 2021 00:55:54 +1100

Last night I published 4 or 5 of blog posts related to the Foreman/Satellite server. Well, it wasn’t a coincidence, it was me cramming the last minute for the Red Hat Satellite 6 Administration exam today. It’s also known as EX403.

Needless to say, I didn’t know what was in the exam, and I can’t share what was in exam I had taken today. What I can share with you is that I passed EX403!

Foreman: Publishing and Promoting Content Views Using Hammer

Sun, 07 Mar 2021 23:46:50 +1100

In this blog post, I’m going to practice publishing and promoting content views using the hammer CLI. I already know how to do this using the Satellite/Foreman web UI.

First, I’m going to create the Base content view for Operations organization and Boston location.

[root@foreman ~]# hammer content-view create \
> --name Base --organization Operations \
> --description 'Base Packages'
Content view created.

[root@foreman ~]# hammer content-view list --organization Operations
----------------|---------------------------|--------------------------|-----------|---------------------|---------------
CONTENT VIEW ID | NAME                      | LABEL                    | COMPOSITE | LAST PUBLISHED      | REPOSITORY IDS
----------------|---------------------------|--------------------------|-----------|---------------------|---------------
6               | Base                      | Base                     | false     |                     |
----------------|---------------------------|--------------------------|-----------|---------------------|---------------

The next step is adding the repos to the content view. I want to add the CentOS 8 BaseOS repo.

Foreman: Creating Software Life-Cycles Using Hammer

Sun, 07 Mar 2021 22:33:50 +1100

In this post, I will create a new life-cycle environment paths for the Operations organization that includes life-cycle environments named Deveopment, QA, and Production.

Let’s list the current life-cycle environment for Operations organization.

[root@foreman ~]# hammer lifecycle-environment list --organization Operations
---|---------|------
ID | NAME    | PRIOR
---|---------|------
6  | Library |
---|---------|------

When we create our first environment, we’ll need to use the ID of the Library, which is 6 in this case. Alternatively, we can just “Library” as the argument to --prior option.

Foreman: Creating Product & Repository Using Hammer

Sun, 07 Mar 2021 15:21:42 +1100

In this blog post, I’m going to show how to add a new product caled EPEL8 and populate it with a repository from EPEL 8.

There should be 3 main steps:

Create a Content-Credentials which stores the package signing key of the product or repository
Create a new Product
Create a new Repository

Firt thing first, let’s create a new content-credentials named RPM-GPG-KEY-EPEL-8 with the contents from the EPEL 8’s GPG signing key.

Foreman: Creating Organization & Location With Hammer

Sun, 07 Mar 2021 14:42:02 +1100

Let’s learn how to create an organization and location on Foreman/Satellite server using the hammer command-line-interface.

In this example, I’m going to create an organization called: Operation and assign its location to Boston.

On the Foreman server, excute the following commands:

[root@foreman ~]# hammer organization create --name Operations
Organization created.
[root@foreman ~]# hammer location create --name Boston
Location created.
[root@foreman ~]# hammer organization add-location --name Operations \
> --location Boston
The location has been associated.

Let’s verify it:

Enable Foreman Ansible Plugin

Sat, 06 Mar 2021 19:55:45 +1100

When I setup Foreman (Satellite) server, I didn’t have Ansible support enabled. Here is how it can be done later on.

If we only need Ansible support, it’s sufficient to just run this command:

# foreman-installer \
--enable-foreman-plugin-ansible \
--enable-foreman-proxy-plugin-ansible

Just a note for myself, I also need Remote Execution enabled if I want to run Ansible playbooks as Job Templates.

# foreman-installer \
--enable-foreman-plugin-remote-execution \
--enable-foreman-proxy-plugin-remote-execution-ssh

Note that the remote execution feature is enabled by default on Foreman/Satellite server. The Smart Proxy or Capsule server, on the other hand, must be specifically enabled with the above installed command.

Learn to Create an RPM Package

Fri, 05 Mar 2021 20:35:14 +1100

The steps to build an RPM package:

Download the source code
Create the spec file (use the rpmdev-newspec command)
Build the package (use the rpmbuild command)
GPG sign the package (use the rpmsign command)
Test the package (use rpm -qip command)

In this post, I’m going to learn to create an RPM package of fpaste-4.0.1.1.tar.gz on Red Hat Enterprise Linux 7 (variant).

First we need to ensure the necessary packages are installed:

Installing Xcode Command Line Tools

Thu, 25 Feb 2021 23:03:17 +1100

I need to use git on command line on macOS 11 (Big Sur), and git comes with command line developer tools. Here is how it can be done on macOS:

❯ xcode-select --install
xcode-select: note: install requested for command line developer tools

On a side note, I notice that every time there is an update to Big Sur, I also have to re-install this Xcode Command Line Tools.

Ref:

kamermanpr/install-xcodeCLT-homebrew-git.md

Setup Proxy for Yum Repository

Wed, 17 Feb 2021 15:42:20 +1100

One of my Red Hat servers is behind proxy with no access to the outside world. This box is registered to a Satellite server to receive software updates.

I want to install Zabbix server on this server using the packages from Zabbix upstream directly. To do this, I need to set the proxy for the Zabbix’s repository. There are a few ways to do this. For my purpose, the best place is to set proxy=proxy_server directly in the .repo file.

BIOS Firmware for ThinkPad P1 Gen1 1.33

Sat, 09 Jan 2021 00:26:45 +1100

Lenovo released the firmeware v1.33 for ThinkPad P1 Gen1 recently which addressed many CVEs.

CHANGES IN THIS RELEASE
  Version 1.33

[Important updates]
- Update includes a security fix.
- Addresses CVE-2020-0587, CVE-2020-0588, CVE-2020-0590,
  CVE-2020-0591, CVE-2020-0592, and CVE-2020-0593.
  (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-0587)
  (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-0588)
  (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-0590)
  (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-0591)
  (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-0592)
  (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-0593)

[New functions or enhancements]
- Updated the Diagnostics module to version 04.15.000.

[Problem fixes]
- Nothing

It’s worth noting that this 1.33 version is not yet available via fwupdmgr. So to update it, just download the firmeware zip file from Lenovo website. Then, manually install it. There are 2 files in the zip, and I only need to install 1 of them.

Create a Client Certificate Key for CockroachDB

Mon, 28 Dec 2020 23:39:57 +1100

CockroachDB has been on my to-check-out list for a very long time. So during this break, I want to spend sometimes to get familiar with it. Who know, maybe it be also be used at work.

I’m checking it out their Rust sample program. In that program, the user’s credential used to connect to the database is done with certificate. So, I need to know how to do generate a user (or also known as client) certificate and key.

Build Hugo Extended for Linux ARM

Sun, 27 Dec 2020 15:54:32 +1100

As of today, there is no official build for Hugo extended for Linux ARM. Therefore, we need to build it ourselves.

Prerequisite:

build-essential package
go1.15.3.linux-arm64 compiler

export VERSION=0.79.1
curl -O -L https://github.com/gohugoio/hugo/archive/v$VERSION.tar.gz
tar -xzf v$VERSION.tar.gz
cd hugo-$VERSION
go build --tags extended
sudo cp hugo /usr/local/bin
Hugo Static Site Generator v0.79.1/extended linux/arm64 BuildDate: unknown

I built Hugo on Odroid C2, and it took over 10 minutes. I think a better way is to cross build Hugo on an x64 machine; but I haven’t tried it yet.

Upgrading oVirt Manager

Sat, 26 Dec 2020 20:48:29 +1100

This upgrade applies to the self-hosted engine of oVirt Manager.

We need to first put the oVirt environment to the global maintenance mode.

[root@trex ~]# hosted-engine --set-maintenance --mode=global

To check the availability of oVirt Manager, run engine-upgrade-check command on the oVirt Manager machine.

[root@ovirtm ~]# engine-upgrade-check
...omitted...
VERB: Queue package ovirt-engine-setup for update
VERB: Building transaction
VERB: Transaction built
VERB: Transaction Summary:
VERB:     install   : ovirt-engine-setup-plugin-cinderlib-4.4.4.5-1.el8.noarch
VERB:     install   : ovirt-engine-setup-base-4.4.4.5-1.el8.noarch
VERB:     install   : ovirt-engine-setup-4.4.4.5-1.el8.noarch
VERB:     install   : ovirt-engine-setup-plugin-websocket-proxy-4.4.4.5-1.el8.noarch
VERB:     install   : ovirt-engine-setup-plugin-vmconsole-proxy-helper-4.4.4.5-1.el8.noarch
VERB:     install   : ovirt-engine-setup-plugin-ovirt-engine-common-4.4.4.5-1.el8.noarch
VERB:     install   : ovirt-engine-setup-plugin-ovirt-engine-4.4.4.5-1.el8.noarch
VERB:     install   : python3-ovirt-engine-lib-4.4.4.5-1.el8.noarch
VERB:     install   : ovirt-engine-setup-plugin-imageio-4.4.4.5-1.el8.noarch
VERB:     remove    : python3-ovirt-engine-lib-4.4.3.12-1.el8.noarch
VERB:     remove    : ovirt-engine-setup-4.4.3.12-1.el8.noarch
VERB:     remove    : ovirt-engine-setup-base-4.4.3.12-1.el8.noarch
VERB:     remove    : ovirt-engine-setup-plugin-cinderlib-4.4.3.12-1.el8.noarch
VERB:     remove    : ovirt-engine-setup-plugin-imageio-4.4.3.12-1.el8.noarch
VERB:     remove    : ovirt-engine-setup-plugin-ovirt-engine-4.4.3.12-1.el8.noarch
VERB:     remove    : ovirt-engine-setup-plugin-ovirt-engine-common-4.4.3.12-1.el8.noarch
VERB:     remove    : ovirt-engine-setup-plugin-vmconsole-proxy-helper-4.4.3.12-1.el8.noarch
VERB:     remove    : ovirt-engine-setup-plugin-websocket-proxy-4.4.3.12-1.el8.noarch
VERB: Closing transaction with commit
Upgrade available.

To update the setup packages, issue the dnf update ovirt*setup* command.

Configure oVirt Manager to Authenticate Against FreeIPA

Sat, 26 Dec 2020 00:08:02 +1100

This is quick note on how to configure an oVirt Manager or RHV Manager to use the FreeIPA to provide user external authentication.

Here’s my servers’ information:

IPA server: ipa.angkorian.io (CentOS 8.3.2011)
oVirt Hosted-Engine: ovirtm.angkorian.io (CentOS 8.3.2011)
IPA user: ovirtadmin

First, open SSH connection to ovirtm as root and ensure that ovirt-engine-extension-aaa-ldap-setup package is installed. Here is a tip to figure out the name of this package - I’d search for ovirt*ldap.

Backing Up a Self Hosted Engine Ovirt

Wed, 23 Dec 2020 23:30:14 +1100

We can create a fullback of oVirt engine without stopping the oVirt infrastructure using the ovirt-backup command.

To do this, ssh to the oVirt hosted-engine and specify this backup scope, the name of backup file and the name of the log file.

[root@ovirtm ~]# engine-backup --scope=all --mode=backup --file=ovirtm-backup_20201223.tgz --log=backup_20201223.log
Start of engine-backup with mode 'backup'
scope: all
archive file: ovirtm-backup_20201223.tgz
log file: backup_20201223.log
Backing up:
Notifying engine
- Files
- Engine database 'engine'
- DWH database 'ovirt_engine_history'
Packing into file 'ovirtm-backup_20201223.tgz'
Notifying engine
Done.

There is more in-depth explanation on how to do the backup of hosted-engine available at Red Hat Customer Portal.

Line Continuation in PowerShell

Wed, 23 Dec 2020 01:41:26 +1100

Usually on bash command-line, the line break character is \. So when I first started to use PowerShell, the \ didn’t work for me. It turned out that the line-break or line continuation in PowerShell is the back tick: `.

Here is an exmaple of PowerShell command to create a DNS delegation in one line:

PS C:\ Add-DnsServerZoneDelegation -Name "example.net" -ChildZoneName "lab.example.net." -NameServer "idm.lab.example.net." -IPAddress 172.25.250.8 -PassThru -Verbose

And we can break it to mutiple line as:

Auto Connect to Hidden Wifi With Networkmanger

Mon, 21 Dec 2020 22:00:21 +1100

If you’re here to find out how to setup network connection to hidden wifi access point, you might want to check this post: How to Connect to Hidden Wifi Using nmcli instead.

This post documents how I fix an issue of wifi connection on a laptop running Gentoo to a hidden access point. The problem is that the wifi connection doesn’t automatically connect despite I’ve set the autoconnect.connection yes.

❯ nmcli con show CamBlue | grep -i autoconnect
connection.autoconnect:                 yes
connection.autoconnect-priority:        0
connection.autoconnect-retries:         -1 (default)
connection.autoconnect-slaves:          -1 (default)

I don’t remember having done anything special on the Fedora laptops connecting to the same the network; and this problem didn’t exit on any of those Fedora machines at all.

Systemd List Failed Units and Services

Tue, 15 Dec 2020 16:49:08 +1100

This is a quick note to list failed services on systemd system.

[root@zilla ~]# systemctl status
● zilla
    State: degraded
     Jobs: 0 queued
   Failed: 1 units
    Since: Fri 2020-09-04 02:20:47 AEST; 3 months 11 days ago
   CGroup: /
           ├─1 /usr/lib/systemd/systemd --system --deserialize 22
           └─system.slice
             ├─httpd.service
             │ ├─21860 /usr/sbin/httpd -DFOREGROUND
             │ ├─21861 /usr/sbin/httpd -DFOREGROUND
             │ ├─21862 /usr/sbin/httpd -DFOREGROUND
             │ ├─21863 /usr/sbin/httpd -DFOREGROUND
             │ ├─21864 /usr/sbin/httpd -DFOREGROUND
             │ └─21865 /usr/sbin/httpd -DFOREGROUND
...

[root@zilla ~]# systemctl list-units --failed
  UNIT         LOAD   ACTIVE SUB    DESCRIPTION
● ipmi.service loaded failed failed IPMI Driver

LOAD   = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB    = The low-level unit activation state, values depend on unit type.

1 loaded units listed. Pass --all to see loaded but inactive units, too.
To show all installed unit files use 'systemctl list-unit-files'.

oVirt - Removing a Storage Domain

Mon, 14 Dec 2020 00:18:57 +1100

This note is, again, for me to remind myself in case I couldn’t recall how to do this in the future.

To remove a storage domain from the cluster, use the following steps:

Click Storage -> Domains
Click on the name of the storage domain to open the details view
Click on the Data Center tab
Click on Maintenance button, then click on OK
The Detach button becomes active, click on it.
Click on Remove

Reference:

Crontab Tip

Sun, 13 Dec 2020 23:01:32 +1100

On Fedora based system, whenever I need help writing a cron task and confused which field is minute, hour, day,..etc, I usually check the /etc/crontab file.

❯ cat /etc/crontab 
SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root

# For details see man 4 crontabs

# Example of job definition:
# .---------------- minute (0 - 59)
# |  .------------- hour (0 - 23)
# |  |  .---------- day of month (1 - 31)
# |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
# |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# |  |  |  |  |
# *  *  *  *  * user-name  command to be executed

Recently, I found an online cron scheduler editor - crontab.guru. It can be used to create a new task expression, or we can use it to verify the existing cron schedule expressions that we have.

Passed Red Hat Virtualization Exam EX318

Wed, 09 Dec 2020 14:32:35 +1100

Another month, another Red Hat exam has been ticked off the list. This time, it’s about the Red Hat Virtualization, a technology based on oVirt.

The code name of the exam is EX318, and as rumours has it, it’s one of the easiest Red Hat exams; I can’t agree more. The exam’s duration is 3 hours; it’s a hand-on closed book exams. The exam is based on Red Hat Virtualization version 4.3.

Update Firmware on Netcom NF18ACV to NC2-R6B021

Sat, 05 Dec 2020 11:28:12 +1100

I like to keep the firmware running on all my devices up to date. New firmware is released to do to main things: fixing bugs and feature enhancing.

Today, I just found out that the modem/router provided by my ISP is running and out of date firmware. The installed firmware is NF18ACV.NC.AU-R6B016.EN released on 2018/05/14. There have been a few new versions of firmware released between then and now, with the latest version being: NC2-R6B021 released on 2020/11/26.

FreeIPA - Adding New User

Fri, 04 Dec 2020 23:08:43 +1100

I have a FreeIPA server with the following information:

FreeIPA server: utility.lab.example.com
FreeIPA realm: LAB.EXAMPLE.COM
FreeIPA domain: lab.example.com

I want to add 2 normal users:

User Login: rhvadmin, First Name: RHV, Last Name: Admin, Password: CentOS123^
User Login: normaluser, First Name: Normal, Last Name: User, Password: CentOS123^


[root@utility ~]# ipa user-add rhvadmin --first RHV --last Admin --password
Password: CentOS123^
Enter Password again to verify: CentOS123^
---------------------
Added user "rhvadmin"
---------------------
  User login: rhvadmin
  First name: RHV
  Last name: Admin
  Full name: RHV Admin
  Display name: RHV Admin
  Initials: RA
  Home directory: /home/rhvadmin
  GECOS: RHV Admin
  Login shell: /bin/sh
  Principal name: rhvadmin@LAB.EXAMPLE.COM
  Principal alias: rhvadmin@LAB.EXAMPLE.COM
  User password expiration: 20201204121711Z
  Email address: rhvadmin@lab.example.com
  UID: 1829600001
  GID: 1829600001
  Password: True
  Member of groups: ipausers
  Kerberos keys available: True

[root@utility ~]# ipa user-add normaluser \
> --first Normal --last User --password
Password: CentOS123^
Enter Password again to verify: CentOS123^
...

The rhvadmin will be asked to change the password on its first login. To prevent this from happening, we can change the user’s password with kpasswd util.

Attaching a Disk to KVM Guest on Command Line

Wed, 02 Dec 2020 13:44:08 +1100

Again, just a quick note to remind myself how to attach a disk to a VM guest from the command line.

The following steps is based on these assumptions:

A spare disk: an LVM volume name db2_data on data volume group
The name/domain of the VM is db2

List the name of the VM guest and available logical volume.

[root@mathvm5 ~]# virsh list | grep db2
 20    db2                            running
[root@mathvm5 ~]# lvs | grep db2
  db2                     vm  -wi-ao----  80.00g
  db2_data                vm  -wi-a----- 128.00g

Run virsh attach-disk command to attach a disk to a VM. Notice that –persistent option is passed to the command so that this new disk will be permanently attached to the VM.

FreeIPA - Adding New DNS Record

Tue, 01 Dec 2020 20:15:00 +1100

I have a FreeIPA server with the following information.

FreeIPA server: utility.lab.example.com
FreeIPA realm: LAB.EXAMPLE.COM
FreeIPA domain: lab.example.com.

I want to insert a few DNS records:

hosta.lab.example.com - 172.25.250.10
hostb.lab.example.com - 172.25.250.11
hostc.lab.example.com - 172.25.250.12
hostd.lab.example.com - 172.25.250.13
bastion.lab.example.com - 172.25.250.254

And I’d like to use the command line to do this.

Acquire the admin’s Kerberos ticket.

[root@utility ~]# kinit admin
Password for admin@LAB.EXAMPLE.COM:

List the DNS zones.

[root@utility ~]# ipa dnszone-find
  Zone name: 250.25.172.in-addr.arpa.
  Active zone: TRUE
  Authoritative nameserver: utility.lab.example.com.
  Administrator e-mail address: hostmaster.lab.example.com.
  SOA serial: 1606798502
  SOA refresh: 3600
  SOA retry: 900
  SOA expire: 1209600
  SOA minimum: 3600
  Allow query: any;
  Allow transfer: none;

  Zone name: lab.example.com.
  Active zone: TRUE
  Authoritative nameserver: utility.lab.example.com.
  Administrator e-mail address: hostmaster.lab.example.com.
  SOA serial: 1606798523
  SOA refresh: 3600
  SOA retry: 900
  SOA expire: 1209600
  SOA minimum: 3600
  Allow query: any;
  Allow transfer: none;
----------------------------
Number of entries returned 2
----------------------------

Find DNS record whose name contains “hosta” (e.g. hosta.lab.example.com)

[root@utility ~]# ipa dnsrecord-find lab.example.com. --name hosta
----------------------------
Number of entries returned 0
----------------------------

Add a record name hosta.lab.example.com with IP 172.25.250.10.

[root@utility ~]# ipa dnsrecord-add lab.example.com. \
> hosta \
> --a-rec 172.25.250.10
  Record name: hosta
  A record: 172.25.250.10

[root@utility ~]# ipa dnsrecord-find lab.example.com. --name hosta
  Record name: hosta
  A record: 172.25.250.10
----------------------------
Number of entries returned 1
----------------------------

Repeat the above steps for hostb, hostc, and hostd

[root@utility ~]# ipa dnsrecord-add lab.example.com. hostb --a-rec 172.25.250.11
  Record name: hostb
  A record: 172.25.250.11
[root@utility ~]# ipa dnsrecord-add lab.example.com. hostc --a-rec 172.25.250.12
  Record name: hostc
  A record: 172.25.250.12
[root@utility ~]# ipa dnsrecord-add lab.example.com. hostd --a-rec 172.25.250.13
  Record name: hostd
  A record: 172.25.250.13

Add a record name bastion.lab.example.com with IP 172.25.250.254

[root@utility ~]# ipa dnsrecord-add lab.example.com. bastion --a-rec 172.25.250.254
  Record name: bastion
  A record: 172.25.250.254

I just realized that all my DNS records do not have reverse records created for them. There are 2 ways to achieve this. First is to create a PTR records for each record above. The second option is to delete the existing record, and create a new one with PTR record created automatically.

Dell Latitude 7400 System BIOS 1.11.1

Sat, 28 Nov 2020 20:59:08 +1100

Dell just released a new BIOS firmware of the Latitude 7400 series. This firmware was released on 23 Nov 2020.

Fixes:

Modified the default settings of the Intel Rapid Storage Technology driver.
Firmware updates to address the Intel Technical Advisory INTEL-TA-00391 (CVE-2020-8753, CVE-2020-8745, CVE-2020-8705, CVE-2020-8757, CVE-2020-8756, CVE-2020-8760, CVE-2020-8751, CVE-2020-8754, CVE-2020-8747, CVE-2020-8746, CVE-2020-8749 CVE-2020-8752, CVE-2020-12303, CVE-2020-12355, and CVE-2020-12356).
Firmware updates to address the Intel Security Advisory INTEL-SA-00358 (CVE-2020-0587, CVE-2020-0591, CVE-2020-0592, and CVE-2020-0593).
Firmware updates to address the Intel Security Advisory INTEL-SA-00381 (CVE-2020-8696 and CVE-2020-8698).
Firmware updates to address the Intel Security Advisory INTEL-SA-00389 (CVE-2020-8694 and CVE-2020-8695).
Firmware update to address CVE-2020-26189.

Enhancements:

Configure iSCSI Target on CentOS 8

Wed, 25 Nov 2020 19:04:38 +1100

I need to have an iSCSI storage to be used by my oVirt lab. The last time I had to create an iSCSI target was during the preparation of the RHCE 7 exam. Therefore, I think this is an opportunity to practice doing this again.

First, install the required package. Then enable the target service, otherwise the target won’t work on the next reboot.

[root@utility ~]# dnf install targetcli -y

[root@utility ~]# systemctl enable target

Run the targetcli command to create an iSCSI target/storage using the storage block (/dev/mapper/data_iscsi LVM volume).

Installing FreeIPA on CentOS 8

Tue, 24 Nov 2020 00:21:10 +1100

This is my note about installing FreeIPA on a CentOS 8 machine. It’s a bit different from the FreeIPA’s installation on CentOS 7, and most importantly there was a problem I came across during the installation and how to fix it.

Configure Static IP

[root@utility ~]# nmcli con mod enp1s0 ipv4.addresses 172.25.250.8/24 \
> ipv4.method manual \
> ipv4.gateway 172.25.250.254 \
> ipv4.dns 172.25.252.1 \
> connection.autoconnect yes
[root@utility ~]# nmcli con up enp1s0

Ensure the hostname of this server exists in /etc/hosts.

How to Expand QCOW2

Sun, 22 Nov 2020 17:07:50 +1100

Today, one of my VMs needs to have its disk increased. I’m using qcow2 as the VM’s storage. Here is one way to expand the storage that it’s been proven to work very well for me.

I already increased this VM’s disk to 30GiB once already, but it wasn’t enough. So here, let’s explode it to 50GiB. The name of the qcow2 file is hosta.qcow2. A friendly reminder that you should alway shave a backup before you perform any critical change such as this one. (I use ZFS, so all I had to do was snapshoting this whole dataset.)

DNS Delegation on Windows Server

Thu, 19 Nov 2020 23:29:44 +1100

One of the requirements to join an Identity Management Server (IdM) to an Active Directory (AD), a DNS delegation needs to be created on AD. With the Red Hat training for RH362, we were taught to use a command-line interface program called dnscmd on AD server. I personally found this command very cumbersome, and I think a better way is to do this DNS delegation using PowerShell cmdlet.

I’ll demonstrate how to do DNS delegation both using dnscmd and PowerShell cmdlet. You can decide yourself which one you find easier to use.

Passed EX362 Identity Management

Thu, 19 Nov 2020 01:47:45 +1100

Today I passed the Red Hat Identity Management exa, EX362, with the score of 233/300.

The material used to prepare for the exam is the RH362 online course, provided Red Hat. At first I wasn’t sure if I should use of the 5 exam credits (as part of one-year training subscription), but it turned out that IdM/FreeIPA is useful and fun to learn.

Here are some tips for this exam:

Using ZFS on an External Drive

Thu, 12 Nov 2020 22:52:58 +1100

I’m a fan of ZFS filesystem. It’s so good that I also use ZFS on most my Linux machines, though it’s painful at time when the ZFS kernel modules fail to compile. Why I like it so much comparing to other file system such as XFS, EXT4, BTRFS? ZFS allows me to quickly do snapshots and efficiently send snapshots over the network, and my nas runs FreeBSD which support ZFS natively.

Display Last Login in Reverse

Sun, 08 Nov 2020 11:36:57 +1100

You’ve been using Linux for a while, so you must have seen or used this command before: cat. It’s used to concatenate files and print on the standard output. But do you know there is another command spelled it reversed tac? tac is like cat, but print files in reverse.

Here is an example which cat could be handy. I need to print out the last login user in reverse. (By the default, it prints the last login first.)

BIOS Firmware for ThinkPad X1 Carbon Gen 6 1.50

Sun, 08 Nov 2020 10:57:52 +1100

Are you still rocking your X1 Carbon Gen 6 in 2020? Well, Lenovo just released a new BIOS firmware 1.50.

Here are changes in this release:

[Important updates]
 - Update includes a security fix.
 - Addresses CVE-2020-8696 and CVE-2020-8698.
   (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-8696)
   (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-8698)
 - Addresses CVE-2020-0587, CVE-2020-0588, CVE-2020-0590, CVE-2020-0591,
   CVE-2020-0592, and CVE-2020-0593.
   (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-0587)
   (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-0588)
   (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-0590)
   (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-0591)
   (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-0592)
   (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-0593)

[New functions or enhancements]
 - Updated the CPU microcode.
 - Updated the Diagnostics module to version 04.15.000.

[Problem fixes]
 Nothing.

It’s worth to note that this new firmware is available on Fedora (33) via fwupdmgr.

Freebsd adduser ERROR - User Disappeared During Update

Sat, 07 Nov 2020 23:53:57 +1100

While creating a new user account on one my servers running FreeBSD 12, I encountered the following error:

root@nas2:~ # adduser
Username: devops
Full name: Ansible Operator  
Uid (Leave empty for default): 
Login group [devops]:      
Login group is devops. Invite devops into other groups? []: 
Login class [default]: 
Shell (sh csh tcsh nologin) [sh]: 
Home directory [/home/devops]:               
Home directory permissions (Leave empty for default): 
Use password-based authentication? [yes]: no
Lock out the account after creation? [no]: no
Username   : devops
Password   : <disabled>
Full Name  : Ansible Operator
Uid        : 1002
Class      : 
Groups     : devops 
Home       : /home/devops
Home Mode  : 
Shell      : /bin/sh
Locked     : no
OK? (yes/no): yes
pw: user 'devops' disappeared during update
adduser: ERROR: There was an error adding user (devops).
Add another user? (yes/no): no
Goodbye!

According to a discussion on a FreeBSD forum, the problem could have caused by the databases being out of sync.

Fix Duplicating Certificates in FreeIPA

Fri, 30 Oct 2020 01:16:00 +1100

While practicing with certificates reqeust using FreeIPA, I came across this duplicated certificates for the first time. This happened because I also practiced the same thing a few weeks ago. Here is how to re-produce this message:

[root@client ~]# ipa-getcert request \
-f /etc/vsftpd/certs/cert.pem \
-k /etc/vsftpd/certs/cert.key \
-K ftp/client.lab.example.net \
-D client.lab.example.net
Certificate at same location is already used by request with nickname "20201008131445".

Because I’m still not familiar yet with FreeIPA on this certificate topic, I turned to Google search and found very useful information on this blog post: Dealing with Duplicate SSL certs from FreeIPA.

BIOS Firmware for ThinkPad P1 Gen1 1.32

Sun, 25 Oct 2020 14:08:20 +1100

Lenovo just released a new BIOS firmware for its ThinkPad P1 Gen 1, v1.32. This version fixes a few issues, as well as update the CPU microcode.

Here is the changes from Lenovo’s website.

CHANGES IN THIS RELEASE
  Version 1.32

[Important updates]
- Addresses CVE-2020-8696, CVE-2020-8698
- Addresses CVE-2020-8694, CVE-2020-8695

[New functions or enhancements]
- Updated the CPU microcode.

[Problem fixes]
- Fixed an issue where system might hang up at POST when some KVM device
  was connected.
- Fixed an issue where the screen might not be displayed on Thinkpad LCD when 
  opened lid just before startup Windows.
- Fixed an issue where system might not boot from network which is connected to
  ethernet of Thunderbolt3 WS Dock when boot mode is Legacy mode.
- Fixed an issue where system might hang at POST when Thunderbolt3 WS Dock
  is attached.
- Fixed an issue where BIOS might generate 0288 beep error.

I haven’t had time to update this 1.32 on my machine yet, though I think the update would be just as smooth as previous release on Fedora 32 system.

Firewalld, nftables, and libvirt on Gentoo

Sat, 17 Oct 2020 11:35:30 +1100

After many and many weeks, I finally got libvirt working on this Gentoo machine. Before revealing how I’ve fixed this problem, let’s go through what the issues were.

On this Gentoo I run Firewalld with nftables as backend. An alternative to nftables is iptables, but since nftables is newer and is becoming the default backend for more and more distribution including Fedora, I think it’s a good thing to adobt it early.

Tmux - Open Terminal Failed Can't Find Terminfo Database

Thu, 15 Oct 2020 00:16:36 +1100

Apart from being an aparent Linux user, I’m also a fan of FreeBSD. A few years ago I challenged myself to perform all work related tasks on a FreeBSD machine for 6 months. It turned out that FreeBSD’s been working out quite well as a general usage work desktop.

Today, I’d like to share a quick solution to a small annoying issue that may or may not affect you when you’re using FreeBSD. Basically, when I ssh from my Linux machine, which uses Alacritty terminal, to the remote FreeBSD machine at work I am not able to resume my tmux session.

Cleaning Up Systemd Journal Logs

Sat, 10 Oct 2020 00:16:23 +1100

“Bad boys, whatcha want. Watcha want, whatcha gonna do when the root is full?”

Actually, what are you gonna do when the journald taking up lots of space? For example, during the operating system upgrade on my desktop, the free space on / is not sufficient.

Error Summary
-------------
Disk Requirements:
   At least 5643MB more space needed on the / filesystem.

So, I check how much space the systemd-journald log was consuming:

Dell Latitude 7400 System BIOS 1.10.1

Thu, 01 Oct 2020 17:40:11 +1000

Just found out that Dell just released the a new firmware, 1.10.1, for the Latitude 7400 series. This firmeware was released since 10 Sep 2020.

Fixes:

Firmware updates to address the Intel Technical Advisory INTEL-TA-00404 (CVE-2020-8758).
Fixed the issue where an error message stating Key Mapping for Console Redirection BIOS is displayed before the Dell logo screen,

Enhancements:

Updated the Embedded Controller Engine firmware.

I’m running Fedora 32 on this laptop. To update the firmeware, just execute fwupdmgr update.

Automating Home Directory With IPA

Thu, 24 Sep 2020 11:02:05 +1000

Nothing excites me than being able to solve a problem on Linux just before bed time. Well, there could be other things, but I couldn’t think of any right now.

Right now, I’m preparing for my next exam - Red Hat Certified Specialist in Identity Management (EX362), and one of the topics is about setting up automated home directory using IdM (or IPA). I tried to follow the course material, but I had troubles getting it working.

Replacing a Disk in a Zpool

Sun, 20 Sep 2020 11:51:35 +1000

ZFS is one of my favorite file systems. I use it at home on my nas server (running FreeBSD) as well as my Fedora 32 desktop. Today, I’m going to show you (and my future self) how to replace a (faulty) disk in a Zpool.

The server I’ll be working on is nas2 and the pool is tank.

List the status of the current pool.

Password:
root@nas2:~ # zpool status tank
  pool: tank
 state: DEGRADED
status: One or more devices could not be opened.  Sufficient replicas exist for
        the pool to continue functioning in a degraded state.
action: Attach the missing device and online it using 'zpool online'.
   see: http://illumos.org/msg/ZFS-8000-2Q
  scan: resilvered 472K in 0 days 00:00:02 with 0 errors on Sun Aug 23 16:17:21 2020
config:

        NAME                      STATE     READ WRITE CKSUM
        tank                      DEGRADED     0     0     0
          mirror-0                DEGRADED     0     0     0
            diskid/DISK-Z4Z46MXG  ONLINE       0     0     0
            620907994788427922    UNAVAIL      0     0     0  was /dev/diskid/DISK-Z1E4ZCM2
          mirror-1                ONLINE       0     0     0
            diskid/DISK-Z1E5PFCH  ONLINE       0     0     0
            diskid/DISK-Z4Z46XQP  ONLINE       0     0     0

errors: No known data errors

From the above output, we can see that one of the disk in mirro-0 vdev was missing. (In fact, it has been removed prior to the system rebooted. I also inserted a new disk to the system.)

Pairing Bluetooth Mouse on Gentoo

Sun, 13 Sep 2020 13:27:58 +1000

Just a few a days ago, I wrote a blog post about Pairing Bluetooth Mouse on Command Line on a Fedora laptop. So why do I need to write another post about doing the same thing on Gentoo? Well, as it turned out, I need a bit more than just turning on the bluetooth service and pairing the mouse. My Gentoo’s installation is very minimal, and I think this gives me an excuse to document on how I’d solve or get this working on Gentoo.

Resizing a GPT Partition

Thu, 10 Sep 2020 16:18:57 +1000

One of my virtual machines runs out of disk space in the root (/) partition, and I want to remove the /home partition and using this free space to resize the root partition.

Nowadays, for any serious systems, I’d use LVM with XFS on top. However, for this test VM, I have a virtual disk with 4 partitions without LVM. Managing partition on LVM is much easier than working the disk partition directly. I can’t remember the last time I had to do this, so here is something to remind my future-self if I need this information again. Hey, if you’re reading this now, this might be useful to you too.

Passed EX415 Linux Security

Thu, 10 Sep 2020 01:34:54 +1000

The exam was 4 hour long. I managed to finish all questions in 3 hours. Fortunately, I found a mistake in the last hour.

I think the EX415 exam wasn’t too difficult and pretty confident that I did well.

The most difficult part: not knowing what I did wrong. Or how the marker scripts would like to see our answers.

I suspected there was a mistake in a question, but who to ask since there is a NDA? If you’re reading this, I can’t even ask or share this suspicion with you. (Again, because of the NDA.)

Pairing Bluetooth Mouse on Command Line

Wed, 09 Sep 2020 23:28:54 +1000

Ever since I’ve switched from Gnome to DWM on my main laptop, I have to perform most things on command line now. I know, right? :P

Anyway, I need to pair a bluetooth mouse, Logi MX Anywhere 2S, with this Fedora laptop. I had a similar post a while back about connecting Bose QC35 to Fedora 29. So this is quite similar to that post.

First, ensure that bluetooth.service is running:

Pfl Provides whatprovides on Gentoo

Fri, 04 Sep 2020 19:05:37 +1000

On Fedora or CentOS, on way to find out what package providing a file we can use yum whatprovides [FILENAME] or dnf whatprovides [FILENAME] on a DNF-aware system.

# dnf whatprovides tmux
Last metadata expiration check: 2:33:06 ago on Wed 09 Sep 2020 09:45:07 PM AEST.
tmux-3.0a-2.fc32.x86_64 : A terminal multiplexer
Repo        : @System
Matched from:
Provide    : tmux = 3.0a-2.fc32

tmux-3.0a-2.fc32.x86_64 : A terminal multiplexer
Repo        : fedora
Matched from:
Provide    : tmux = 3.0a-2.fc32

I really need this similar tool on Gentoo, and it looks like the emerge command doesn’t have this function built it. Fortunately, there is a utility called e-file (provided by pfl package) which kinda provides this whatprovides option as in yum and dnf.

Locking Package Version with DNF Versionlock

Sun, 30 Aug 2020 23:51:07 +1000

While newer version of a package on Linux system is generally a good thing, and we should upgrade it, there is times when we should hold on to the older version.

For instance, Fedora 32 just released a newer version of the kernel package 5.8.4 recently, and with this version, the zfs module, version 0.8.4, can’t be built. Therefore, if your Fedora system uses ZFS, like some of my machines, you’ll end up not seeing any ZFS dataset or pools.

How to Enable Persistent Logging for Systemd Journal

Sat, 29 Aug 2020 11:01:31 +1000

On RHEL 7/8, CentOS 7/8 and even Ubuntu (??), by default the journal log data is stored only in memory (/run/log/journal/ directory).

There are 2 ways to retain the journal log messages. The first one is to set the variable Storage to persistent in the /etc/systemd/journald.conf.

[Journal]
Storage=persistent

Then restart the systemd-journald service.

Another solution is simpler and it looks like it’s the recommended way of achieving this. All we have to do is to create a directory, /var/log/journal (with correct ownership and permission), and journald will automatically store the log messages there.

Thunderbolt Firmware for ThinkPad X1 Carbon 6 1.20

Thu, 13 Aug 2020 18:23:20 +1000

A quick note to remind ThinkPad X1 Carbon 6 users that Lenovo just released a new firmware for the Thunderbolt on this laptop. And, it’s available via fwupd if you run Fedora (possibly also available on Ubuntu).

[root@benji ~]# fwupdmgr update
• Thunderbolt Controller has the latest available firmware version
Upgrade available for Embedded Controller from 0.1.20 to 0.1.21
20KHCTO1WW must remain plugged into a power source for the duration of the update to avoid damage. Continue with update? [Y|n]: 
Downloading…             [***************************************]
Decompressing…           [***************************************]
Authenticating…          [***************************************]
Updating Embedded Controller…************************************]
Scheduling…              [***************************************]
Successfully installed firmware
• Intel Management Engine has the latest available firmware version
• SAMSUNG MZVLW256HEHP-000L7 has no available firmware updates
• System Firmware has the latest available firmware version

An update requires a reboot to complete. Restart now? [y|N]:

All you need to do is rebooting the machine.

SELinux Error ValueError: Port already Defined

Mon, 27 Jul 2020 14:44:53 +1000

Today, I want to run the httpd server on a custom port, 8002 on a CentOS 7 server. Of course, all my system has SELinux in enforcing mode.

In order for the httpd to bind on port 8002, we need to add this port to the httpd_port_t port type list.

First let’s confirm that port 8002 is not yet in the http_port_t list:

[root@servera ~]# semanage port -l | grep ^http
http_cache_port_t              tcp      8080, 8118, 8123, 10001-10010
http_cache_port_t              udp      3130
http_port_t                    tcp      80, 81, 443, 488, 8008, 8009, 8443, 9000

We know from the manual semanage-port(8), to add a port to an SELinux port type list, we run the following command:

BIOS Firmware for ThinkPad P1 Gen1 1.31

Mon, 27 Jul 2020 00:21:18 +1000

It seems like Lenovo releases a new BIOS firmeware every month for its ThinkPad, at least for the ThinkPad P1 Gen1. On July 21, the BIOS firmware version 1.31 was released.

CHANGES IN THIS RELEASE
  Version 1.31

[Important updates]
- Address CVE-2020-0548, 
 (https://cve.mitre.org//cgi-bin//cvename.cgi?name=CVE-2020-0548)
- Address CVE-2020-0549, 
 (https://cve.mitre.org//cgi-bin//cvename.cgi?name=CVE-2020-0549)
- Address CVE-2020-0543, 
 (https://cve.mitre.org//cgi-bin//cvename.cgi?name=CVE-2020-0543)

[New functions or enhancements]
- Updated the CPU microcode.

[Problem fixes]
- Fixed an issue where Force PXE boot by Intel AMT did not work.

This firmware supports both ThinkPad P1 Gen1 and ThinkPad X1 Extreme 1:

How to Change Private Key Passphrase

Mon, 20 Jul 2020 09:37:41 +1000

To change the passphrase on your default RSA key:

➜ ssh-keygen -p
Enter file in which the key is (/home/kenno/.ssh/id_rsa):
Enter new passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved with the new passphrase.

Note that if you have more a different key, you can either supply it at the “Enter file in which key is” prompt or provide this file to the ssh-keygen argument with the -f option. E.g.:

Changing LUKS Passphrase

Sun, 12 Jul 2020 23:07:26 +1000

In my previous blog post, Managing File System Encryption with LUKS, I showed how to create an encrypted partition (of disk) using LUKS.

Today, I’d like to show you how we can change the passphrase on this LUKS encrypted partition and keeping this passphrase (key) in the same slot.

While I’m writing this blog post, I cannot remember how to do this, and I’m going to try to figure this out without doing the Google search. :)

Dell Latitude 7400 System BIOS 1.9.1

Thu, 02 Jul 2020 20:19:32 +1000

Update BIOS firmware version 1.9.1 is available for Dell Latitude 7400. This firmware was released on 30 June 2020. It is marked Urgent and contains the following fixes and enhancements:

Fixes:

Fixed the issue where the system cannot detect the Intel Software Guard Extensions (SGX) device when SGX is enabled.
Firmware updates to address security advisory INTEL-SA-00295 (CVE-2020-0531, CVE-2020-0532, CVE-2020-0533, CVE-2020-0535, CVE-2020-0536, CVE-2020-0537, CVE-2020-0538, CVE-2020-0539, CVE-2020-0540, CVE-2020-0545, CVE-2020-0594, CVE-2020-0595, CVE-2020-0596, and CVE-2020-8674).
Firmware updates to address the Intel Security Advisory INTEL-SA-00320 (CVE-2020-0543).
Firmware updates to address the Intel Security Advisory INTEL-SA-00329 (CVE-2020-0548 and CVE-2020-0549).
Firmware updates to address the Intel Security Advisory INTEL-SA-00322 (CVE-2020-0528 and CVE-2020-0529).

Enhancements:

Managing Security Risk on RHEL 8

Tue, 30 Jun 2020 11:16:11 +1000

This blog post is mainly about my practicing of managing security risk on a RHEL system, especially learning how to use the occasionally option passed to YUM command. It is probably not a good resource teaching how to properly manage security risks in general.

Identify all critical, important, and moderate security notices on this server.

[root@puppet2 ~]# yum updateinfo --security
Updating Subscription Management repositories.
Red Hat Enterprise Linux 8 for x86_64 - Supplementary (RPMs)                                  21 kB/s | 2.1 kB     00:00
Red Hat Enterprise Linux 8 for x86_64 - AppStream (RPMs)                                      27 kB/s | 2.8 kB     00:00
Red Hat Enterprise Linux 8 for x86_64 - BaseOS (RPMs)                                        475  B/s | 2.4 kB     00:05
EPEL8 x86_64                                                                                  28 kB/s | 2.8 kB     00:00
Updates Information Summary: available
    2 Security notice(s)
        2 Important Security notice(s)

Determine how many security-related packages are available for this machine.

Installing USBGuard on Gentoo

Mon, 29 Jun 2020 00:56:47 +1000

Let’s find out the name of the package using the awesome eix command, and install that package.

 ~ # eix usbguard
* sys-apps/usbguard
     Available versions:  ~0.7.6-r1 ~0.7.8 {bash-completion dbus ldap policykit static-libs systemd}
     Homepage:            https://github.com/USBGuard/usbguard
     Description:         Daemon protecting your computer against BadUSB

 ~ # emerge --ask sys-apps/usbguard

These are the packages that would be merged, in order:

Calculating dependencies... done!

!!! All ebuilds that could satisfy "sys-apps/usbguard" have been masked.
!!! One of the following masked packages is required to complete your request:
- sys-apps/usbguard-0.7.8::gentoo (masked by: ~amd64 keyword)
- sys-apps/usbguard-0.7.6-r1::gentoo (masked by: ~amd64 keyword)

For more information, see the MASKED PACKAGES section in the emerge
man page or refer to the Gentoo Handbook.

It looks like we need to unmask usbguard.

Managing File System Encryption with LUKS

Sun, 28 Jun 2020 21:31:48 +1000

Last year, I already wrote a blog post about the same topic: Configure Encrypted Storage With LUKS, and I had used fdisk to create a disk partition. In this post, I’ll use parted to achieve the same thing.

I’m going to perform this operation on a server called servera on a disk device /dev/vdb.

First, let’s verify that vdb is available and has no partition:

[root@servera ~]# parted -l
...

Error: /dev/vdb: unrecognised disk label
Model: Virtio Block Device (virtblk)
Disk /dev/vdb: 1074MB
Sector size (logical/physical): 512B/512B
Partition Table: unknown
Disk Flags:

Use parted to create a partition on vdb using the whole disk.

Install Ansible on Gentoo

Sun, 28 Jun 2020 02:19:29 +1000

Gentoo provides a package called app-admin/ansible for Ansible. To install it, just run:

❯ sudo emerge --ask app-admin/ansible

Note that unlike Ansible package on CentOS/Fedora, there is no default ansible.cfg provided with the Gentoo Ansible package.

❯ ansible --version
ansible 2.9.9
  config file = None
  configured module search path = ['/home/kenno/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python3.7/site-packages/ansible
  executable location = /usr/lib/python-exec/python3.7/ansible
  python version = 3.7.7 (default, May  9 2020, 19:52:18) [GCC 9.2.0]

Reference:

How to Label Ext4 Filesystem

Sat, 20 Jun 2020 19:40:24 +1000

I have a 2TB drive, when connecting to my Fedora workstation, it’s mounted using the UUID of the partition as the following:

# mount | grep sde1
/dev/sde1 on /run/media/kenno/f59ffb93-5a92-4af9-a9b5-19ca3bb8aa37 type ext4 (rw,nosuid,nodev,relatime,seclabel,uhelper=udisks2)

I think it’ll look nicer if it’s mounted with a shorter name, e.g. ‘Podcast’.

The filesystem for this drive is ext4. To create a label on the ext4 filesystem, we can use a program called e2label. The exact command is e2label device [ volume-label ] according to the man page.

Move or toggle current window to second monitor in DWM

Thu, 18 Jun 2020 16:31:16 +1000

I’ve switched to use DWM, Dynamic Windows Manager, from GNOME on my laptop since the beginning of this month. So far I really enjoyed it.

Here are some commands I needed to know since I have an external screen connected ot this machine.

To change the focus to previous/next screen:

Mod1 + ,
Mod1 + .

To move applications from a screen to another, just add Shift key:

Mod1 + Shift + ,
Mod1 + Shift + .

References:

Upgrading STM32 Nucleo F401RE Firmware on Linux

Mon, 15 Jun 2020 22:44:47 +1000

I’ve been meaning to pick up a micro-controller and work on it again. About 5 years ago when I first encountered Arduino, I spent sleepless night learning about it, and creating things from DIY weather station, world clock, light sensor, etc. Fast forward to the current days, I almost forgot everything I learned. But we can always re-learn, or can’t we?

Tonight, I found an Stm32 Nucleo F401RE micro-controller, and I want to start by updating the firmware on it (admittedly, this is the easiest thing to do). ST provides a tool called STW-LINK007, which can be freely downloaded from its website, to flash the firmware on a range of its micro-controllers. I have also written a blog post to update a similar micro-controller, STM32F4-Discovery, in the past.

SELinux Non-Default Home Directory Location

Mon, 15 Jun 2020 14:16:37 +1000

On most my systems I created a user called devops with its home directory created at /srv/devops. And on Fedora or CentOS systems, those home directories have their SELinux context set correctly when created. Recently, I found out that on all 3 machines so far, the SELinux context has been reverted.

~# ls -lZ /srv
total 0
drwx------. 5 devops devops system_u:object_r:var_t:s0    127 Oct 30  2019 devops

It should have had the same context as the normal user kenno in /home directory:

How to Create Multiple Directories with Incrementing Numbers in Names

Tue, 09 Jun 2020 17:39:46 +1000

I need to create 20 empty directores with the following name: dvd01, dvd02, dvd03,…, dvd20.

My first thought was to use for loop, but then I decided to do a quick Google search, and found something more elegant:

$ mkdir dvd{01..20}

That’s cool, isn’t it?

Reference:

How to create multiple directories with incrementing numbers in a single command?

Dell Latitude 7400 System BIOS 1.7.4

Mon, 08 Jun 2020 15:19:11 +1000

Dell released a new BIOS firmware version 1.7.4 for the Latitude 7300 and 7400 on May 22, 2020. This release is again marked Urgent and contains the following fixes and enhancements:

Fixes:

Firmware updated to address CVE-2020-5363

Enhancements:

Updated the Embedded Controller Engine Firmware

This version 1.7.4 is already available on Fedora 32 via fwupdmgr tool.

[root@matht436 ~]# fwupdmgr refresh
Fetching signature https://cdn.fwupd.org/downloads/firmware.xml.gz.jcat
Downloading…             [***************************************]
Fetching metadata https://cdn.fwupd.org/downloads/firmware-00558-stable.xml.gz
Downloading…             [***************************************]
Successfully downloaded new metadata: 1 local device supported
[root@matht436 ~]# fwupdmgr update
• Thunderbolt Controller has no available firmware updates
• SSDPEKKF512G8 NVMe INTEL 512GB has no available firmware updates
Upgrade available for System Firmware from 1.7.3 to 1.7.4
Latitude 7400 must remain plugged into a power source for the duration of the update to avoid damage. Continue with update? [Y|n]:
Downloading 1.7.4 for System Firmware...
Fetching firmware https://fwupd.org/downloads/a397a5b5fb47d0411ce59e5a4550940681c741ebf8b601f9c90934e4a7ce4e29-Latitude_7X00_1.7.4.cab
Downloading…             [***************************************] Less than one minute remaining…
Decompressing…           [***************************************]
Authenticating…          [***************************************]
Updating System Firmware…[             /                         ]
Scheduling…              [***************************************]
Successfully installed firmware
• Touchpad has no available firmware updates
• Unifying Receiver has no available firmware updates

An update requires a reboot to complete. Restart now? [y|N]:

There was no problem after rebooting.

BIOS Firmware for ThinkPad P1 Gen1 1.30

Mon, 08 Jun 2020 12:08:44 +1000

Lenovo just released an updated BIOS firmware version 1.30 for ThinkPad P1 Gen1 on June 3rd.

The changes in this v1.30 release are:

CHANGES IN THIS RELEASE
  Version 1.30

[Important updates]
- Update includes a security fix.
- Address CVE-2020-0529, 
  (https://cve.mitre.org//cgi-bin//cvename.cgi?name=CVE-2020-0529)
- Address CVE-2020-0528, 
  (https://cve.mitre.org//cgi-bin//cvename.cgi?name=CVE-2020-0528)

[New functions or enhancements]
- Updated the Diagnostics module to version 04.12.001.

[Problem fixes]
- Fixed an issue where USB keyboard connected via Thunderbolt WS Dock might not be used at BIOS POST.

This firmware supports both ThinkPad P1 Gen1 and ThinkPad X1 Extreme 1:

Create Disk Partition With GNU Parted

Wed, 20 May 2020 22:11:47 +1000

My favourite tool to create disk partitions on Linux is c[fg]disk. cfdisk used to create MBR based partition, and cgdisk is for GPT one.

Today, I want to learn to use another tool called GNU Parted.

After plugging an external disk, we can use udiskctl command to identify the disk device.

# udisksctl status
MODEL                     REVISION  SERIAL               DEVICE
--------------------------------------------------------------------------
Samsung SSD 850 EVO 250GB EMT01B6Q  S21MNXAG919308T      sda
ST2000DM001-1ER164        HP51      Z4Z46TMA             sdb
ST2000DM001-1ER164        HP51      Z4Z46W3E             sdc
Samsung SSD 850 EVO 250GB EMT01B6Q  S21MNXAG919312Y      sdd
Samsung SSD 840 EVO 250G  0309      533144424E4541443837343335324120 sde

The last Samsung SSD 840 (/dev/sde) is the one that I’m going to work with.

BIOS Firmware for ThinkPad X1 Carbon Gen 6 1.48

Sat, 16 May 2020 19:10:33 +1000

On May 15, Lenovo released a new BIOS firmware for ThinkPad X1 Carbon Gen 6. The latest of the version of the firmware is 1.48. (There previous version 1.47 was withdrawn for some unknown reason.)

Changes in this releases:

CHANGES IN THIS RELEASE
  Version 1.48

[Important updates]
- Update includes a security fix.

[New functions or enhancements]
- Updated the Diagnostics module to version 04.12.001.

[Problem fixes]
- Fixed an issue where Force PXE boot by Intel AMT does not work.

As of today, this new firmware is not yet available via LVFS on Fedora 32. So for those who are impatient like me, we can install this firmware ourselves. Warning: In no way will I be liable if your brick your own machine when you follow this guide!

BIOS Firmware for Thinkpad P1 Gen1 1.29

Sat, 16 May 2020 14:52:11 +1000

It’s almost exactly one month from the last time Lenovo released (v1.28 of ) the BIOS firmware for ThinkPad P1 Gen 1. Apparently, v1.28 firmware has been marked “Withdrawn” according to this n2eul21w.txt.

The changes in this release v1.29 is:

CHANGES IN THIS RELEASE
  Version 1.29

[Important updates]
- Addresses CVE-2019-0154
  (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-0154)
  Refer to Lenovo's Security Advisory page for additional information about
  LEN-27714 "Multi-vendor BIOS Security Vulnerabilities".
  (https://support.lenovo.com/us/en/product_security/LEN-27714)

[New functions or enhancements]
- Updated the CPU microcode.

[Problem fixes]
- Nothing

This firmware supports both ThinkPad P1 Gen1 and ThinkPad X1 Extreme 1 listed below:

Create Folder Recursively With Powershell

Thu, 14 May 2020 20:20:18 +1000

Let’s say I want to create the following directories: C:/Program Files/MiKTeX 2.9/tex/latex/math using PowerShell because, as you may guess it, it’s a Windows directory structure.

Here’s the command to do that:

PS C:\> New-Item -Type Directory -Path "C:/Program Files/MiKTeX 2.9/tex/latex/math"

The command seems simple enough. So why did I create this post? Well, guess what? I have to Google this out for the 3rd time this month. From now, if I need to look it up again, I can just go to https://blog.khmersite.net/tags/powershell/.

Remove Kernels on Fedora

Sun, 26 Apr 2020 00:11:01 +1000

I’m still running Fedora 31 on my main desktop though Fedora 32 beta has been out for a while. The only reason that stops me from jumping to F32 now is because ZFS 0.8.3 is not compatible with the kernel 5.6.* on F32. Rumor has it, ZFS 0.8.4 will support kernel 5.6.

Tonight, while doing the system update with sudo dnf update -y on F31 desktop, I noticed that the kernel for F31 is now kernel-5.6.6-200.fc31.x86_64. Wait, what? I didn’t interrupt the update process, and let it run till finish.

Delete a Local User Account With PowerShell

Wed, 22 Apr 2020 16:43:56 +1000

I need to delete a user from the PowerShell terminal and I don’t know how to do it.

Well, fear no more, let’s have a quick read on Remove-LocalUser on how to do this.

The command to delete the user is Remove-LocaUser.

Remove-LocalUser
      [-InputObject] <LocalUser[]>
      [-WhatIf]
      [-Confirm]
      [<CommonParameters>]

Remove-LocalUser
      [-Name] <String[]>
      [-WhatIf]
      [-Confirm]
      [<CommonParameters>]


Remove-LocalUser
      [-SID] <SecurityIdentifier[]>
      [-WhatIf]
      [-Confirm]
      [<CommonParameters>]

Here is an example of deleting a local user called simba.

Getting rid of old initrd files on Ubuntu

Tue, 21 Apr 2020 10:30:55 +1000

Occasionally I see some of our Ubuntu machines having /boot partition filled up by the initrd files generated from old kernels which no longer were no longer installed on the machines.

root@matht232:/boot# uname -a
Linux matht232 5.3.0-40-generic #32~18.04.1-Ubuntu SMP Mon Feb 3 14:05:59 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

root@matht232:/boot# dpkg -l linux-image-\* | grep ^ii
ii  linux-image-5.3.0-40-generic           5.3.0-40.32~18.04.1  amd64        Signed kernel image generic
ii  linux-image-generic-hwe-18.04-edge     5.3.0.46.102         amd64        Generic Linux kernel image

root@matht232:/boot# ls -1 /boot
config-5.3.0-40-generic
config-5.3.0-46-generic
grub
initrd.img-3.13.0-46-generic
initrd.img-4.15.0-88-generic
initrd.img-4.4.0-101-generic
initrd.img-4.4.0-122-generic
initrd.img-4.4.0-87-generic
initrd.img-5.3.0-40-generic
lost+found
System.map-5.3.0-40-generic
System.map-5.3.0-46-generic
vmlinuz-5.3.0-40-generic
vmlinuz-5.3.0-46-generic

I tried to remove these initrd files manually, and they were generated again when a new kernel is installed. I haven’t figured how did this happened, until today!

New System BIOS for Dell Latitude 7400 1.7.3

Sun, 12 Apr 2020 00:14:37 +1000

Dell just released a new system BIOS version 1.7.3 on April 8 for Dell Latitude 7400. This release is marked as Urgent, and comes with the following fixes and enhancements:

Fixes:

Fixed the issue where the Type-C port works from BIOS Boot Menu with external USB port disabled.
Fixed the issue that there is no user interface for wireless connection in BIOS Connect cloud SOS interface.
Fixed the issue where the system stops responding on Dell logo when SMM Security mitigation and Secure Boot is enabled.
Fixed the issue where the system is not able to update the BIOS from BIOS Boot Menu with SMM Security Mitigation enabled.

Enhancements:

New BIOS Firmware for ThinkPad P1 G1 1.28

Sat, 11 Apr 2020 15:40:30 +1000

So another new post, another new firmware update? You bet it is!

Early this month, Lenovo just released another BIOS firmware for ThinkPad P1 Gen 1. It looks like Lenovo has fixed a few bugs comparing to the the previous firmware release in March.

CHANGES IN THIS RELEASE
  Version 1.28

[Important updates]
- Addresses CVE-2019-0154 (https://cve.mitre.org//cgi-bin//cvename.cgi?name=CVE-2019-0154)
  Refer to Lenovo's Security Advisory page for additional information about 
  LEN-27714 "Multi-vendor BIOS Security Vulnerabilities"
  (https://support.lenovo.com/us/en/product_security/LEN-27714)
- Addresses CVE-2020-0548 (https://cve.mitre.org//cgi-bin//cvename.cgi?name=CVE-2020-0548)
- Addresses CVE-2020-0549 (https://cve.mitre.org//cgi-bin//cvename.cgi?name=CVE-2020-0549)
- Addresses CVE-2020-0543 (https://cve.mitre.org//cgi-bin//cvename.cgi?name=CVE-2020-0543)

[New functions or enhancements]
- Updated the CPU microcode.

[Problem fixes]
- Fixed an issue where system might hang after Intel AMT Control is set
  to Disabled by ThinkPad Setup.

Let’s update the firmware, shall we?

Gentoo Luks Fails Kernel 5.6

Sat, 11 Apr 2020 01:05:06 +1000

My Gentoo based Linux laptop which is still running the older kernel 5.3.15. A short while back, I had a failed attempt to upgrade the kernel to 5.4.2 as the disk which encrypted with dm-crypt couldn’t be decrypted on boot. Since the older kernel 5.3.15 was working fine and free time was I what I lacked of, it seemed logical to just not doing anything about it.

Today while updating all the packages on my Gentoo laptop, I notice there was a newer kernel available: 5.6.3. So let’s try to install this newest kernel again and see if the issue with Luks/dm-crypt still persists.

List Open Ports on FreeBSD

Wed, 08 Apr 2020 12:13:07 +1000

On Linux to list running services and open ports, I either use netstat or ss (socket stat?) most recently.

Though netstat is available on FreeBSD, the syntax is completely different.

Today, I have the need to list the running services with the port display. On FreeBSD, we can do this using sockstat command.

root@bsd1:~ # sockstat -4 -l
USER     COMMAND    PID   FD PROTO  LOCAL ADDRESS         FOREIGN ADDRESS      
minio    minio      49274 10 tcp46  *:9000                *:*
root     sendmail   675   4  tcp4   127.0.0.1:25          *:*
root     sshd       672   4  tcp4   *:22                  *:*
ntpd     ntpd       616   21 udp4   *:123                 *:*
ntpd     ntpd       616   22 udp4   149.171.180.154:123   *:*
ntpd     ntpd       616   25 udp4   127.0.0.1:123         *:*
root     syslogd    523   7  udp4   *:514                 *:*

Here are some other options which can be passed to the sockstat command:

New BIOS Firmware for ThinkPad X1 Carbon G6 1.46

Tue, 31 Mar 2020 21:52:12 +1100

Lenovo has “quietely” released another firmware (1.46) for ThinkPad X1 Carbon Gen 6.

Changes in this release:

CHANGES IN THIS RELEASE
  Version 1.46

[Important updates]
- Update includes a security fix.

[New functions or enhancements]
  Nothing.

[Problem fixes]
  Nothing.

I am not able to find out what the “important security fix” is. However, I’m happy to report that the firmware update went well on X1 Carbon Gen 6 running Fedora 31.

New BIOS Firmware for ThinkPad P1 G1 1.27

Fri, 27 Mar 2020 21:31:55 +1100

If you’re still running ThinkPad P1 Gen 1 (Type 20MD, 20ME) like me, there is an exciting news, at least to me. Lenovo just released a new BIOS/UEFI firmware updated at version 1.27 on Mar 20, 2020.

Changes in this releases:

CHANGES IN THIS RELEASE
  Version 1.27

[Important updates]
- Addresses CVE-2019-0185 (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-0185)
   Refer to Lenovo's Security Advisory page for additionalinformation about
   LEN-27714 "Multi-vendor BIOS Security Vulnerabilities".
   (https://support.lenovo.com/us/en/product_security/LEN-27714)
- Security fix addresses LEN-29406 "ST Microelectronics TPM Firmware ECDSA
   Signature Generation Vulnerability". 
   Refer to Lenovo's Security Advisory page for additionalinformation.
   (https://support.lenovo.com/us/en/solutions/LEN-29406)
- Addresses CVE-2019-14607 (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-14607)

[New functions or enhancements]
- Updated the CPU microcode.
- Supported BIOS password authentication before entering into MEBx.

[Problem fixes]
- Nothing.

On a Fedora (31/32) laptop, to update the firmware is very easy nowaday. Here are the 2 commands to run:

New BIOS UEFI Firmware for ThinkPad X1 Carbon G6 1.45

Sun, 16 Feb 2020 23:40:55 +1100

Though a new firmware was release for ThinkPad X1 Carbon G6 since last month, 2020/01/23, I only found about this today. Unlike the firmware for Dell’s laptop, once can easily update it with fwupmgr if your Linux system supports it.

Here’s what’s changed in this release.

CHANGES IN THIS RELEASE
  Version 1.45
<1.45>
 UEFI: 1.45 / ECP: 1.20
- (Fix) Fixed an issue where a system hardware controller device might disappear
        at 2nd boot.

To update it on Fedora 31, run:

New System BIOS for Dell XPS 13 7390 1.1.13

Sun, 09 Feb 2020 22:42:21 +1100

Dell released a new System BIOS firmware for Dell XPS 13 2-in-1 version 1.1.3 at the end of last year. This release marked as Urgent, and it fixed the following issues (as taken from Dell’s site):

Fixed the incorrect panel size information in the BIOS setup menu.
Fixed the issue where the MAC Address Override fails during the Preboot eXecution Environment (PXE) boot process.
Change default setting of “Enable Thunderbolt (and PCIe behind TBT) pre-boot modules” to disabled by default

If your laptop runs Windows 10 and has Dell Update utilities installed, this System BIOS firmware update process is very simple. You just need to run this utility and click on Update button.

NVIDIA Driver on Fedora 31 with Kernel 5.4

Sun, 02 Feb 2020 22:08:50 +1100

There’s been problem with NVIDIA driver on my computer running Fedora 31 ever since the kernel has hit version 5.4.*. The issue is that the NVIDIA driver version 435.21, which is installed from rpmfusion-nonfree, can’t be built with kernel 5.4.

Here is the version of the akmod-nvidia package:

[root@watamem ~]# dnf info akmod-nvidia
Last metadata expiration check: 1:48:11 ago on Sun 02 Feb 2020 08:13:26 PM AEDT.
Installed Packages
Name         : akmod-nvidia
Epoch        : 3
Version      : 435.21
Release      : 1.fc31
Architecture : x86_64
Size         : 22 k
Source       : nvidia-kmod-435.21-1.fc31.src.rpm
Repository   : @System
From repo    : rpmfusion-nonfree
Summary      : Akmod package for nvidia kernel module(s)
URL          : http://www.nvidia.com/
License      : Redistributable, no modification permitted
Description  : This package provides the akmod package for the nvidia kernel modules.

And here is what happened when I tried to build the NVIDIA driver:

Mounting exFat Filesystem on Fedora

Sat, 21 Dec 2019 02:01:43 +1100

Just a note to remind myself to install packages required to have Fedora based system to recognize SD cards or other drives formatted using exFAT.

# dnf install fuse-exfat exfat-utils -y

After the above 2 packages installed, just reinsert the SD cards, no reboot is required.

New BIOS Firmware for ThinkPad P1 1.25

Sun, 08 Dec 2019 01:02:27 +1100

It looks like Lenovo just released a new firmware for ThinkPad P1 Gen1 again.

Here is the changes in this 1.25 release:

CHANGES IN THIS RELEASE Version 1.25

[Important updates]
- Update includes security fixes.
- Addresses CVE-2019-0151 (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-0151)
- Addresses CVE-2019-0152 (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-0152)
- Addresses CVE-2019-0123 (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-0123)
- Addresses CVE-2019-0124 (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-0124)
- Addresses CVE-2019-0117 (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-0117)
- Addresses CVE-2019-0184 (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-0184)

[New functions or enhancements]
- Updated the CPU microcode.
- Updated Regulatory Information.

[Problem fixes]
- Nothing.

Unlike previous BIOS version 1.24 update, I wanted to try to just use the fwupdmgr command utility to do it. It turned it out it was quite simple and straight forward.

How to Update Packages on Arch Linux

Sat, 07 Dec 2019 23:35:13 +1100

Finally, I got Arch installed on my ThinkPad X220. This also means that I will need to learn how to install and update software from scratch again. But that’s the fun part, isn’t it? :)

Like many other distros, before we can update the installed packages, we need to update the software database (i.e. updated list from the repositories):

[root@tora ~]# pacman -Syy

Note the above command is similar to apt-get update in Debian/Ubuntu.

How to Install Ansible on Centos 8

Sat, 09 Nov 2019 10:06:03 +1100

On most Linux distribution, Ansible can be installed either using python3-pip or ansible package.

I’m going to show how to get Ansible installed using the second method on CentOS 8.

First add the EPEL repository to the CentOS 8 server.

# yum localinstall https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm

Next, install ansible package:

# yum install ansible
Last metadata expiration check: 0:00:49 ago on Sun 10 Nov 2019 09:33:22 PM AEDT.
Dependencies resolved.
=======================================================================================================================
 Package                           Arch                  Version                        Repository                Size
=======================================================================================================================
Installing:
 ansible                           noarch                2.8.5-2.el8                    epel                      15 M
Installing dependencies:
 python3-babel                     noarch                2.5.1-3.el8                    AppStream                4.8 M
 python3-jinja2                    noarch                2.10.1-2.el8_0                 AppStream                538 k
 python3-jmespath                  noarch                0.9.0-11.el8                   AppStream                 45 k
 python3-markupsafe                x86_64                0.23-19.el8                    AppStream                 39 k
 python3-pyasn1                    noarch                0.3.7-6.el8                    AppStream                126 k
 libsodium                         x86_64                1.0.18-2.el8                   epel                     162 k
 python3-bcrypt                    x86_64                3.1.6-2.el8.1                  epel                      44 k
 python3-pynacl                    x86_64                1.3.0-5.el8                    epel                     100 k
 sshpass                           x86_64                1.06-9.el8                     epel                      27 k
Installing weak dependencies:
 python3-paramiko                  noarch                2.4.3-1.el8                    epel                     289 k

Transaction Summary
=======================================================================================================================
Install  11 Packages

Total download size: 21 M
Installed size: 104 M
Is this ok [y/N]:

Let’s confirm that the installation went ok by checking the version of ansible:

How to Label an XFS Filesystem

Sun, 27 Oct 2019 23:49:40 +1100

When I plugged in an external drive to my laptop, the drive was displayed as a string consits random letters and numbers. Here is an example:

❯❯❯ df -Th | grep sdb
/dev/sdb1               xfs       481M   26M  456M   6% /run/media/kenno/5428b182-c92e-466b-89d2-b5b31b80ba48

Though the drive worked perfectly fine, I think it’s ugly, and I wanted to properly give it a good name. Let’s call it externo.

But how to do this? You may not believe it, I forgot how to do this. In fact, I couldn’t rememer when the last time I had to (re)label a file system. Fear not,Google can come to the rescue!

Create a User Account with PowerShell

Thu, 24 Oct 2019 04:23:19 +1100

Today I learned how to create a user account on Windows 10 using PowerShell. Let’s create a small exercise to demonstrate how can this be easily done.

Task: “Create a local user account named ’localaccount’ with the password BlueHat. This new user should have admin privilege.”

First, launch the PowerShell (terminal?), by running as Administrator.

The password will be stored in a variable called $Password:

$Password = Read-Host -AsSecureString
*******

Now we’re ready to create a new local account:

CTDB Not Starting Up on CentOS 7

Sun, 13 Oct 2019 23:25:57 +1100

While preparing for my Red Hat Gluster Storage Administration exam (EX236), I got stuck at a section of configuring IP failover with CTDB Clustered Trivial Database) for Samba. The problem is that I coudldn’t get the ctdb service running on my home lab running CentOS 7 and a newer version of ctdb.

This problem occurs on the following platform and package version:

CentOS Linux release 7.7.1908 (Core)
ctdb 4.9.1-6.el7

# systemctl status ctdb
● ctdb.service - CTDB
   Loaded: loaded (/usr/lib/systemd/system/ctdb.service; enabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Sun 2019-10-13 23:17:46 AEDT; 3min 7s ago
     Docs: man:ctdbd(1)
           man:ctdb(7)
  Process: 1335 ExecStart=/usr/sbin/ctdbd_wrapper start (code=exited, status=1/FAILURE)

Oct 13 23:17:35 serverb.rh236.local systemd[1]: Starting CTDB...
Oct 13 23:17:35 serverb.rh236.local ctdbd[1348]: CTDB logging to location file:/var/log/log.ctdb
Oct 13 23:17:46 serverb.rh236.local ctdbd_wrapper[1335]: Timed out waiting for initialisation - check logs
Oct 13 23:17:46 serverb.rh236.local systemd[1]: ctdb.service: control process exited, code=exited status=1
Oct 13 23:17:46 serverb.rh236.local systemd[1]: Failed to start CTDB.
Oct 13 23:17:46 serverb.rh236.local systemd[1]: Unit ctdb.service entered failed state.
Oct 13 23:17:46 serverb.rh236.local systemd[1]: ctdb.service failed.

Here is the congent from /var/log/log.ctdb log:

New BIOS Firmware for ThinkPad P1 1.24

Mon, 07 Oct 2019 01:17:14 +1100

I’ve been relying on Gnome Software Center to let me know when new ThinkPad P1 firmware is available. Up until today, there is no new firmware available since the last update back in August 2019.

However, I stumbled on a post on reddit r/thinkpad, someone mentioned the BIOS 1.26 had been released for X1 Extreme/P1 Gen 2. This made me wonder if there was also new version of BIOS for the P1 Gen 1 that I have. Of course, there is a new BIOS firmware available: 1.24.

grub2-editenv: error environment block too small

Tue, 10 Sep 2019 01:14:12 +1000

As the title says when I tried to generate grub on a machine running Fedora 31 using UEFI, I was presented with this error:

# grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg 
Generating grub configuration file ...
grub2-editenv: error: environment block too small.
...

I didn’t know what had caused it. However, it seemed like an easy fix was to remove the grubenv file.

# rm /boot/efi/EFI/fedora/grubenv
# grub-editenv /boot/efi/EFI/fedora/grubenv create
# grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg 
Generating grub configuration file ...
Adding boot menu entry for EFI firmware configuration
done

By the way, as a word of caution, if you have a similar problem, please don’t just copy and paste the command above and run it. It may make your sitution worse.

feh WARNING: abc.png - No Imlib2 loader for that file format

Sun, 01 Sep 2019 16:00:52 +1000

As the title says, I cannot use feh to open a PNG image. feh on this machine can’t open a JPG image either. Let’s see what’s wrong.

I should notice that this problem occured on a machine running Gentoo. :D

First, let’s check if feh is installed using my favorite tool called eix:

~ ❯❯❯ eix feh
[I] media-gfx/feh
     Available versions:  3.1.1 ~3.1.3 ~3.2 ~3.2.1^t {curl debug exif test xinerama}
     Installed versions:  3.1.1(11:11:04 PM 04/14/2019)(-curl -debug -exif -test -xinerama)
     Homepage:            https://feh.finalrewind.org/
     Description:         A fast, lightweight imageviewer using imlib2

According to the above information, feh:3.1.1 is already installed. It also mentions that feh use imlib2 library.

Configure Encrypted Storage With LUKS

Thu, 29 Aug 2019 22:30:12 +1000

I’m currently preparing for the Red Hat Certified Specialist in Security: Linux exam (EX415). One of the exam objectives is about storage encryption using LUKS.

Here’s my note learning about LUKS. It’s not meant to be a guide which you should copy and paste and run it on your production system.

Suppose I have a new disk (/dev/vdb) attached to my server and I’d like to use it as an encrypted storage using LUKS. Here is how I’d do it.

How I Update Hugo on My Machine

Sun, 25 Aug 2019 12:03:11 +1000

I run hugo hot off the development branch. Periodically I need to checkout the code and re-build it. I find myself having to google to do this almost all the time. So today, I’m gonna document this here so I can quickly look it up next time I want to update hugo.

The hugo code has already be cloned to the following location in my desktop:

mkdir -p $HOME/dev/go
cd $HOME/dev/go
git clone https://github.com/gohugoio/hugo.git

Here are the commands to update the hugo code, rebuild and reinstall it:

How to Generate a GPG Key

Mon, 19 Aug 2019 14:32:13 +1000

GPG, the GNU Privacy Guard, can be used to digitally sign email, encrypt files. GPG is also used to sign RPM package.

In this post, I’ll write a short instruction on how to generate a new GPG key on RHEL or CentOS 7.

The command we need to generate the GPG key is gpg. This program is provided by gnupg2, and it should have aready been installed in most system.

Upgrading Kernel Issues and Fixes on Gentoo

Tue, 06 Aug 2019 23:33:03 +1000

Today I decided to upgrade the kernel (gentoo-sources) from 4.19.64 to 5.2.6 on my old ThinkPad X220. Apart from a few hiccups, everything went quite smoothly. I already have a blog post about upgrading the kernel on Gentoo, so I’ll skip many things here.

First, ensure the sys-kernel/gentoo-sources-5.2.6 is installed:

# emerge -av =sys-kernel/gentoo-sources-5.26

After the above package installed, we should be able to list it:

~ ❯❯❯ eselect kernel list
Available kernel symlink targets:
  [1]   linux-4.14.63-gentoo-r1
  [2]   linux-4.14.65-gentoo
  [3]   linux-4.14.78-gentoo
  [4]   linux-4.14.83-gentoo
  [5]   linux-4.19.27-gentoo-r1
  [6]   linux-4.19.44-gentoo
  [7]   linux-4.19.52-gentoo
  [8]   linux-4.19.57-gentoo
  [9]   linux-4.19.64-gentoo *
  [10]  linux-5.2.6-gentoo

Let’s select linux-5.2.6-gentoo as the version we’d like to switch to:

New Device Firmware Available for ThinkPad P1

Sun, 04 Aug 2019 22:29:42 +1000

It looks like there are more device firmware available for Lenovo ThinkPad P1 (and X1 Extreme).

Based on the list from Gnome Software Center, the available firmware are:

Thunderbolt Firmware N2ETF12W
System Firmware (Embedded Controller) 0.1.11
System Firmware (?) 0.1.23

It’s time to update all of them on my P1.

New Firmware 1.21 Available for ThinkPad P1

Sat, 08 Jun 2019 11:48:18 +1000

I run Fedora 30 on my ThinkPad P1 with i3 as a windows manager. Today, I switched to Plasma to test something out. While running plasma, I launched (Gnome) Software centre to check if there was any firmware update for this P1. To my surprise, there was one available: 1.21 released on April 29, 2019.

Feel free to find out what’s new in this firmware at the following link: P1 (Type 20MD, 20ME) Laptop (ThinkPad).

New Firmware for Sony A6500 v1.06

Tue, 28 May 2019 23:11:24 +1000

In early March this year Sony released version 1.05 firmware for Sony A6500. Today, I found out that Sony has a newer version of the firmware available, 1.06.

This time around, Sony didn’t clearly specify what’s changed in this version beside just one point:

Improves the overall stability of the camera

To update the firmware, you’ll need either a Windows or a Mac machine. Here is a link to download the firmware from Australian Sony website:

Destroying Unknown Status Pod in OpenShift

Fri, 17 May 2019 10:09:40 +1000

Here’s a quick tip to remove an OpenShift pod with “Unknown” status.

Suppose this is the output when I run oc get pods:

~ ❯❯❯ oc get pods
NAME            READY     STATUS              RESTARTS   AGE
dothe-4-bjq8v   0/1       ContainerCreating   0          5h
dothe-4-ghttj   1/1       Unknown             0          15h

~ ❯❯❯ oc delete pod dothe-4-ghttj
pod "dothe-4-ghttj" deleted
~ ❯❯❯ oc get pods
NAME            READY     STATUS              RESTARTS   AGE
dothe-4-bjq8v   0/1       ContainerCreating   0          5h
dothe-4-ghttj   1/1       Unknown             0          15h

Let’s try deleting the bad pod again with --force option:

Fedora 30 Beta With ZFS Support

Thu, 18 Apr 2019 19:18:30 +1000

Up until today, I have been running Fedora 29 with the kernel 4.9. The current version of the kernel on Fedora 29 is 5.0. However, I had to stick with the 4.20 version for a very long while due to a thing I did a short while back. So what is that thing? Well, at one point ZFS (stable) no stopped working with the new kernel on Fedora 29. At then, I had a choice to either keep running older version of the kernel or trying out the new version of ZFS (testing). I opped for the second option. When Fedora 29 bumped its kernel to 5.0, unfortunately, the testing ZFS didn’t support this version of the kernel.

Connect Bose QC35 to Fedora 29 Using i3

Mon, 18 Mar 2019 16:43:38 +1100

I have a very nice pair of headphones Bose QC35 and would like to connect it to my laptop running Fedora 29. It’s normally quite easy to pair up the headphones and the laptop when running Gnome or KDE as the desktop environment. But, how to do this from a minimal tiling windows manager such as i3? In this post, I’m going briefly show how one can do that.

First ensure that the bluetooth service is running:

New Firmware v1.05 Available for Sony Alpha 6500

Sat, 02 Mar 2019 23:47:20 +1100

Unlike FujiFilm, Sony doesn’t often release updated firmware for its cameras. For that reason, I’m almost never bothered to check if there is new one available for my Sony Alpha 6500 (a6500).

However, out of the blue, I decided to just have a quick look up and found out that Sony has release v1.05 firmware for the A6500 since February last year. The firmware on my camera was v1.04.

The most notable updates for the v1.05 firmware includes:

Install Ansible on Freebsd

Thu, 21 Feb 2019 14:11:22 +1100

This post briefly explains how to install Ansible on a FreeBSD host.

I’m going to install Ansible in a virtual environment using Python 3. (If you still use Python 2, it’s time to start migrating to Python 3 now.)

$ sudo pkg install python36
$ mkdir ~/dev/python3-venv
$ python3 -m venv ~/dev/python3-venv/ansible

Next, activate the Python venv (ansible), and start installing Ansible using pip:

$ source ~/dev/python3-venv/ansible
$ pip install ansible

You may or may not need to update pip module as I did. In my case, Python complains that I have older version of pip. To update pip, just run:

Install Lmod on Gentoo

Tue, 19 Feb 2019 20:42:41 +1100

Lmod is not available in Gentoo’s portage. This blog post will document how I got Lmod installed on my Gentoo machine.

First requirement is to install lua. I picked lua 5.2 as I had problem when experimenting with Lua 5.1. To install lua-5.2.3 from portage, run:

# emerge -av =dev-lang/lua-5.2.3

If you have multiple versions of Lua installed, make sure to select this lua 5.2.3 as the default version using eselect:

Autostart a KVM Domain

Wed, 13 Feb 2019 10:55:04 +1100

Again this is a quick note to explain myself how to set a kvm (domain/vm) autostart when the server boots up.

To list autostart domains:

virsh list --autostart

To set a domian, e.g. dhcp1, to autostart:

virsh autostart dhcp1

To disable autostart for a domain (e.g. named dhcp1):

virsh autostart dhcp1 --disable

Ref:

KVM: Start a Virtual Machine / Guest At Boot Time

ZFS Testing on Fedora

Thu, 31 Jan 2019 11:37:20 +1100

When Fedora release kernel 4.20.*, the ZFS 0.7.12 could no longer compiled. Accoriding to the ZFS release page at Github zfs-0.7.12 is only compartible iwth kernels 2.6.32 - 4.19.

At first I was going to just wait for the 0.8.0 release, and continue to use kernel 4.19. However, Fedora keeps releasing the updates of kernel 4.20. As of this writing, the current version of the kernel on Fedora 29 is 4.20.6-200. At the same time, zfs-0.8.0 is still not yet released.

NVME Not Found on Boot With UEFI

Thu, 17 Jan 2019 20:32:55 +1100

A quick note to remind myself how to get NVME recognized on Dell XPS 15 9570 on Gentoo.

Make sure to add the kernel BLK_DEV_NVME options.

NVM Express block device (BLK_DEV_NVME)
CONFIG_BLK_DEV_NVME:
The NVM Express driver is for solid state drives directly
connected to the PCI or PCI Express bus. If you know you
don't have one of these, it is safe to answer N.
To compile this driver as a module, choose M here: the
module will be called nvme.
Symbol: BLK_DEV_NVME [=m]
Type : tristate
Prompt: NVM Express block device
Location:
-> Device Drivers
Defined at drivers/nvme/host/Kconfig:1
Depends on: PCI [=y] && BLOCK [=y]

Ref:

How to Connect to Hidden Wifi Using nmcli

Tue, 15 Jan 2019 18:00:14 +1100

Today I need to setup a wifi connection on a laptop to my home network with hidden SSID. Like so many things that I only have to do it once in a while, I couldn’t remember how to do it. So this blog post is something to remind me in the future should I need to do it agian.

Here is one way to do it, thanks to this Stack Overflow question. (Alternatively, check man nmcli and man nmcli-examples which have detailed information):

Fix Dbus Daemon Autolaunch Was Disabled at Compile Time

Tue, 15 Jan 2019 15:03:36 +1100

When I tried to run notify-send on my laptop running Gentoo, it didn’t work and was given the following message:

$ notify-send 'hello'
Connecting to D-Bus failed: Using X11 for dbus-daemons autolaunch was disabled at compile time, set your DBUS_SESSION_BUS_ADDRESS instead

How do one set DBUS_SESSION_BUS_ADDRESS? Accoridng to this, it can be done by running:

$ export $(dbus-launch)

However, I want to also have D-Bus compiled with X11 support.

First let’s verify if D-Bus service is running:

Upgrade Kernel on Gentoo

Mon, 14 Jan 2019 20:17:30 +1100

Today I’m going to document how I built and installed kernel 4.20.1 a Gentoo laptop, Dell XPS 15 9570.

This blog post is not intended to be a tutorial or even a guide. I’m very new to Gentoo, and have been spoiled by Ubuntu and Fedora for not needing to compile my own kernel. :)

Anyhow, it’s very likely that I’ll need to compile the kernel again on Gentoo, and therefore I think having some sorts of documents is better than nothing at all.

Gentoo Eix Tool

Mon, 14 Jan 2019 19:52:29 +1100

A utility that I use quite a lot on a Gentoo system is called eix. This tool allows me to search for packages by name and list all available flags.

The document on the Gentoo Wiki is great and has detailed explanation about it.

In this blog post, I’m just going to write down what I did to get it installed.

I want to set its flag to use qlite.

# echo 'app-portage/eix sqlite' > /etc/portage/package.use/eix

Then proced with the installation:

How to remove Ctrl-M characters from files

Sun, 06 Jan 2019 20:30:17 +1100

A short while back, after exporting my blog from WordPress to Hugo I noticed that there were some weird ^M characters in some files as shown in the following screenshot in blue.

This is a special character, CTRL+M and can be removed using sed or vim. Using vim we can replace/substitute a text with the following command:

%s/MATCH-TEXT/WITH-NEW-TEXT/g

Therefore, we should be able to replace ^M, by typing CTRL+V then CTRL+M, with an empty space as so:

Getting Started With Armadillo C++ Library

Tue, 01 Jan 2019 02:09:12 +1100

Yesterday while I was running system update on my home desktop, I noticed the armadillo package has been upgraded. I was pretty sure I never requested to have it installed on this desktop. The package name, though, looks very interesting.

Upon looking it up, I found out that Armadillo is a C++ library for linear algebra. Coincidentally, I’ve been reviewing C++ during this end of year holiday. So it’s like a very good time to try this library out.

Compiling C++ Statically

Mon, 24 Dec 2018 18:05:28 +1100

The first programming language I took when I started my undergraduate study in computer science was C. The second language was C++, taken in the following semester.I really liked C/C++ back then, but I never got a chance to actually use C/C++ in any real-life project. After transfering to the University of Auckland in New Zealand, I had to pick up Java as almost all computer science courses taught in Java back in early 2000.

Ansible Automation Exam EX407

Sat, 15 Dec 2018 21:18:44 +1100

Last week I passed the Red Hat exam, Certificate of Expertise in Ansible Automation (EX407), and I just want to note down my experience of taking this exam.

The exam duration is 4 hours, and I was able to complete all the questions in 3 hours and 45 minutes. Was it because questions were difficult? No, on the contrary in my opinions questions aren’t very difficult, comparing to the Ansible learning material in D407. Speaking about learning material, to prepare for the EX407 exams, I went through 2 courses: D407R (recording) and D407VC (Video Classroom). Apart from that, I have also been using Ansible at work for quite awhile.

Upgrading Freebsd 11.2 to 12.0-RELEASE

Wed, 12 Dec 2018 21:07:08 +1100

FreeBSD 12.0-RELEASE was released today, and that means it’s time to upgrade 2 of FreeBSD 11.2 machines to this latest version.

One of my FreeBSD boxes is a desktop used at work, and the upgrade went well without any issues. In this post, I’m going to document how the upgrade is done on my nas server at home.

First ensure that the FreeBSD is up to date:

root@nas:~ # freebsd-update fetch
src component not installed, skipped
Looking up update.FreeBSD.org mirrors... 2 mirrors found.
Fetching metadata signature for 11.2-RELEASE from update1.freebsd.org... done.
Fetching metadata index... done.
Inspecting system... done.
Preparing to download files... done.

No updates needed to update system to 11.2-RELEASE-p6.

Begin to perform the upgrade:

Fix puppet-firewalld: puppet fails with unknown type of string error

Tue, 18 Sep 2018 12:00:21 +0000

To manage firewalld on a desktop, I use the module created by Craig Dunn available at https://github.com/crayfishx/puppet-firewalld. Recently, I came across this issue for the second time after restarting puppetserver:

# puppet agent -vt
Info: Using configured environment 'production'
Info: Retrieving pluginfacts
Info: Retrieving plugin
Info: Loading facts
Error: Could not retrieve catalog from remote server: Error 500 on SERVER: Server Error: Evaluation Error: Error while evaluating a Resource Statement, Evaluation Error: Error while evaluating a Resource Statement, Could not autoload puppet/type/firewalld_rich_rule: /etc/puppetlabs/code/modules/firewalld/lib/puppet_x/firewalld/property/rich_rule_action.rb:10: unknown type of %string
            if value.keys.sort != %i[action type]
                                    ^ at /etc/puppetlabs/code/modules/firewalld/manifests/init.pp:135:7 on node mathtxx
Warning: Not using cache on failed catalog
Error: Could not retrieve catalog; skipping run

Previously, the problem seem to disappear after awhile, and because I’ve been occupied with other tasks, I kinda forgot about it.

Becoming a Red Hat Certified Engineer

Thu, 13 Sep 2018 23:55:20 +0000

After spending almost 8 weeks preparation, I finally took the Red Hat Certified Engineer (RHCE) exam yesterday. I found the questions are not very difficult, however it’s very easy to make mistakes. The exam duration is 3.5 hours and I had about 15 minutes left when I completed the last question.

Having done the the Red Hat Certified System Administrator (RHCSA) before, I remember if you receive an email from Red Hat with an attachment, that implies that you pass the exam. Well, the grade came back within 2 hours after exam, and this time there was no attachment. Oh my!

Update ThinkPad X1 Carbon G6 BIOS Update on Fedora

Thu, 13 Sep 2018 23:04:42 +0000

As a ThinkPad fan, I really like X1 Carbon (G6). I run Fedora 28 on it, and almost everything runs flawlessly. One issue that bothers me a lot is problem with suspend. The X1 Carbon G6 supports S0i3 instead of the S3. Without the S3, when the laptop is put to suspended, the battery continue to drain and sometimes the cpu fan keeps running.

Fortunately, this issue has been recently addressed by Lenovo through firmware update. According to the wiki.archlinux.org, S3 can be enabled in BIOS from BIOS version 1.30 or newer.

Connect to a WPA2-Enterprise Connection Using nmcli

Mon, 27 Aug 2018 14:11:38 +0000

This is like a re-post of a question from askubuntu.com. To get to that post, I usually had to google it. So, I’ll post it here so I know where to look for when I need it again.

At work, we use WPA2-Enterprise for wireless connection. To create a new connection on my laptop with wlp3s0 as Wifi device, follow this step:

# nmcli con add type wifi ifname wlp3s0 con-name work-wifi ssid work-ssid

# nmcli con edit id work-wifi
nmcli> set ipv4.method auto
nmcli> set 802-1x.eap peap
nmcli> set 802-1x.phase2-auth mschapv2
nmcli> set 802-1x.identity myusername
nmcli> set 802-1x.password mypassword
nmcli> set wifi-sec.key-mgmt wpa-eap
nmcli> save
nmcli> activate

That’s it if you know how to do it.

How to Generate SELinux Policy Manual Page

Sun, 26 Aug 2018 23:21:33 +0000

It seems that by default, SELinux policy manpage is not available. Here’s how to make it available.

First install selinux-policy-devel package
Then generate the man page by running:
# sepolicy manpage -a -p /usr/share/man/man8 
-a : all domains
-p : path to store the manpage (by default it’s /tmp)
/usr/share/man/man8 – section 8 of manpage is for system admin command
Create or update manual page index caches
# mandb
Benefit
# man -k _selinux (or e.g. ”man httpd_selinux“)

RHEL Recovering the Root Password

Sun, 12 Aug 2018 14:24:05 +0000

Early last year I started a blog post about the preparation for Red Hat Certified System Administrator (RHCSA) exam. My intention back then was to have more posts follow suit about the exam topics. Like many things in life, things don’t always go according to plan. That was the only post, but I passed the RHCSA exam.

Today, I’m going to start another new post about the preparation for the Red Hat Certified System Engineer (RHCSE) exam. I already booked an exam which is taking place on September 12. The exam is 3.5 hours long and cover a broader range than before.

How to change shell in Fedora

Mon, 23 Jul 2018 21:35:11 +0000

If your search engine take you to this page, chances are you get used to use chsh to change user’s shell. On Fedora (28 at least), chsh is not available by default. You can install util-linux-user according to this post to get the chsh command.

However, there is another alternative which I didn’t even think of - use usermod command.

Here’s how I did it to change to zsh shell:

$ sudo usermod -s /usr/bin/zsh kenno
$ getent passwd kenno
kenno:x:1000:1000:Oh Kenno:/home/kenno:/usr/bin/zsh

Just log out and log back in. That’s it.

Changing the urxvt font size on the fly (take 2)

Thu, 05 Jul 2018 21:31:24 +0000

A while back I posted an instruction on how to change the font size in urxvt (terminal emulator) on the fly. In that post, I used a perl extension from https://github.com/simmel/urxvt-resize-font. Tonight, I tried to setup this extension on a brand new laptop running Fedora 28. For some reason, it doesn’t work at all. Luckily, I found another perl extension which works quite well.

Here’s how I got it working on this Fedora 28, with Sway tiling windows manager (instead of i3 because I run Wayland with this Fedora 28).

Upgrading my nas from FreeBSD 11.1-RELEASE to 11.2-RELEASE

Sat, 30 Jun 2018 20:33:54 +0000

FreeBSD 11.2-RELEASE was released a few days ago. This means it’s time to upgrade the FreeBSD running on my nas.

For the most part, this was all what I did:

# freebsd-update -r 11.2-RELEASE upgrade
# freebsd-update install
# reboot
# freebsd-update install

After it’s been upgraded, I also need to update the Zpool.

root@nas:~ # zpool status
  pool: zroot
 state: ONLINE
status: Some supported features are not enabled on the pool. The pool can
        still be used, but some features are unavailable.
action: Enable all features using 'zpool upgrade'. Once this is done,
        the pool may no longer be accessible by software that does not support
        the features. See zpool-features(7) for details.
  scan: scrub repaired 0 in 0h0m with 0 errors on Tue Jan 23 23:54:42 2018
config:

        NAME        STATE     READ WRITE CKSUM
        zroot       ONLINE       0     0     0
          gpt/zfs0  ONLINE       0     0     0

errors: No known data errors

Let’s upgrade the zpool zroot as suggested:

Playing movie with Dragon player on Fedora 28

Sun, 24 Jun 2018 22:52:56 +0000

With fresh installation of Fedora 28 I wasn’t able to play any downloaded Japanese animations with the default movie player – Dragon player. My other machine which also runs Fedora 28 could play the movie fine. Without any doubts I must have installed some additional codecs on that machine. But which codecs? Like last time, Google I must search.

I’m going to write this post so I wouldn’t have to repeatedly search for the same solution.

How to reload tmux config

Fri, 22 Jun 2018 15:58:05 +0000

To reload tmux’s config without quitting and starting it again, we can hit Ctrl + B then :. Once the we get the prompt just run:

:source-file ~/.tmux.conf

Ref: https://sanctum.geek.nz/arabesque/reloading-tmux-config/

Install MATE Desktop on CentOS 7

Wed, 13 Jun 2018 01:26:00 +0000

Tonight I started to review the learning material for Red Hat System Administration III to prepare for RHCSE exam. I need a machine with GUI, and all my CentOS 7 VMs are headless. So let’s install the GUI on it, shall I?

First install epel repo, if it’s not yet installed:

# yum install epel-release -y

Then install the 2 groups:

# yum groupinstall "X Window system" -y
# yum groupinstall "MATE Desktop" -y

Tip, if “I” can’t remember the names of the groups, I can run this command to list all available groups:

How to set timezone in FreeBSD 12.0

Mon, 28 May 2018 17:11:37 +0000

FreeBSD 12.0 install media :20180208 misses a lot of timezone file. E.g. it doesn’t have /usr/share/zoneinfo/Australia/Sydney.

Ensure: zoneinfo package is installed.

Then run:

# tzsetup

And confirm: Fri Feb 16 00:19:48 AEDT 2018

Where is the Startup folder in Windows 10?

Wed, 23 May 2018 10:18:08 +0000

Here’s one way to locate it:

Click on the Windows Start Menu icon. Type “Run”, and click on Run (Desktop App).
Then, when the Run dialog box presents, just enter shell:common startup and hit the Enter key

Ref: http://www.thewindowsclub.com/startup-folder-in-windows-8

Fix: VirtualBox installation fails on macOS High Sierra 10.13.4

Tue, 08 May 2018 11:12:27 +0000

Just a quick note to remind myself how I fixed the problem installing VirtualBox 5.2.10 on a Mac laptop running 10.13.4.

The installation seemed to go well until it reached the end and reported failing to install. I’ve had this issues for a few weeks already and Google for solution seems to have hit and missed until today. I finally found a solution posted here: https://github.com/docksal/docksal/issues/417.

Basically, I need to go the System Preferences and tick the box to allow ‘System software from developer “Oracle America, Inc.” was block from loading’.

Make Github code viewer more pleasant on Firefox on FreeBSD

Sun, 22 Apr 2018 13:56:08 +0000

Ever since I have FreeBSD 12 installed on a spare laptop, I notice that this is the most frequently used portable machine at home. (Of course, I still use my main desktop, which runs Fedoda 27, for everything.) I think one of the main reasons is that I like the experiences when I started using Linux years ago – not everything works out of the box, and sometimes I’m forced to learn and understand better about an issue before it can be fixed.

Ansible 2.5.0 { "changed": false, "cmd": "None -s system-product-name", "msg": "[Errno 2] No such file or directory

Sat, 31 Mar 2018 21:15:48 +0000

I just updated Ansible to version 2.5.0 tonight, and I came across this issue when I tried to run a playbook for an Ubuntu 16.04 machine:

PLAY [Ansible Playbook for configuring odroid.***.com] ***************************************************************************************

TASK [Gathering Facts] *****************************************************************************************************************************
fatal: [odroid.***.com]: FAILED! => {"changed": false, "cmd": "None -s system-product-name", "msg": "[Errno 2] No such file or directory: 'None'", "rc": 2}

According to the issue #37911, the remote system doesn’t have the dmidecode package installed. This is true in my case, and it can be verified as the following:

Automount External Drive on OS X

Thu, 22 Mar 2018 23:37:36 +0000

At work, we want to backup an external disk that’s connected to the Mac machine using rsnapshot. In order to do that, the external drive needs to be mounted, and this happens when a user logs in to the Mac. The problem is that when nobody logs in, the external drive is not mounted and rsnapshot will fail.

The fix should be easy if there is away to mount the external drive without a user logs in. It turns out that on OS X (tested on High Sierra) we can set a flag to have the external drives get mounted when the Mac boots up.

How to change FreeBSD Firefox user agent

Tue, 13 Mar 2018 17:50:15 +0000

This laptop runs FreeBSD 12.0 current. The version of the installed Firefox is 59, which is pretty new isn’t it? Well, that’s not new or good enough to browse outlook.office365.com email. What happened is that, the Outlook web based email would just automatically switch to class Outlook web access. This problem is not unique to Outlook email, even some work related websites refuse to load correctly on Firefox running FreeBSD.

How to extend ZFS partition

Sun, 11 Mar 2018 11:37:07 +0000

I have a FreeBSD server which used to run of a smaller SSD drive. When replaced with a larger capacity SSD by using dd command to clone the disk, there is free space allocated. I want to extend the existing zroot pool to use this space. The following describes how I achieve this with the help of a forum post.

Let’s list some information about the zroot pool:

root@nas:~ # zfs list zroot
NAME    USED  AVAIL  REFER  MOUNTPOINT
zroot  4.88G  50.8G   144K  none

List the partition scheme of the drive I’d like to extend my zroot zpool with:

SELinux is preventing mpd from getattr access on the directory /root/.config.

Fri, 02 Mar 2018 00:04:21 +0000

What? Why does mpd want to access /root/.config? What’s MPD? It’s a daemon for playing music. It runs as a service, which I connect to with either ncmp or ncmpcpp.

Here’s the full SETroubleshoot detail:

SELinux is preventing mpd from getattr access on the directory /root/.config.

*****  Plugin catchall (100. confidence) suggests   **************************

If you believe that mpd should be allowed getattr access on the .config directory by default.
Then you should report this as a bug.
You can generate a local policy module to allow this access.
Do
allow this access for now by executing:
# ausearch -c 'mpd' --raw | audit2allow -M my-mpd
# semodule -X 300 -i my-mpd.pp

Additional Information:
Source Context                system_u:system_r:mpd_t:s0
Target Context                unconfined_u:object_r:config_home_t:s0
Target Objects                /root/.config [ dir ]
Source                        mpd
Source Path                   mpd
Port                          
Host                          watamem.local
Source RPM Packages           
Target RPM Packages           
Policy RPM                    selinux-policy-3.13.1-283.26.fc27.noarch
Selinux Enabled               True
Policy Type                   targeted
Enforcing Mode                Enforcing
Host Name                     watamem.local
Platform                      Linux watamem.local 4.15.4-300.fc27.x86_64
                              #1 SMP Mon Feb 19 23:31:15 UTC 2018 x86_64 x86_64
Alert Count                   2
First Seen                    2018-03-01 19:37:10 AEDT
Last Seen                     2018-03-01 19:40:15 AEDT
Local ID                      95638a12-2d84-4060-9339-8f05c61c619e

Raw Audit Messages
type=AVC msg=audit(1519893615.831:1060): avc:  denied  { getattr } for  pid=23997 comm="mpd" path="/root/.config" dev="dm-0" ino=1703951 scontext=system_u:system_r:mpd_t:s0 tcontext=unconfined_u:object_r:config_home_t:s0 tclass=dir permissive=0


Hash: mpd,mpd_t,config_home_t,dir,getattr

The version of MPD that causes this issue is: 0.20.10 on Fedora 27. I’m pretty sure it was working last week and I didn’t have to do anything. So what’s changed? Well, it seems like this could be a very old problem as reported int bug 1325502. Basically, when mpd is started, it tries to read the MPD configuration file (mpd.conf). According to the man page for mpd.conf, the configuration file should be read in the following order:

FreeBSD 12 : Can't update packages size mismatch

Thu, 15 Feb 2018 23:10:26 +0000

It’s another night with another FreeBSD problem. Well, I could just use Linux like Ubuntu or Void, but then things would just work. Where is the fun? 😉

So, I’ve been having problem with upgrading or installing new binary packages on a machine running FreeBSD 12.0 for a few days now.

root@vansota:~ # pkg upgrade
Updating FreeBSD repository catalogue...
FreeBSD repository is up to date.
All repositories are up to date.
Checking for upgrades (13 candidates): 100%
Processing candidates (13 candidates): 100%
The following 6 package(s) will be affected (of 0 checked):

New packages to be INSTALLED:
	p5-Locale-gettext: 1.07

Installed packages to be REINSTALLED:
	xorg-server-1.18.4_6,1 (needed shared library changed)
	xf86-input-synaptics-1.9.0 (options changed)
	texinfo-6.5,1 (options changed)
	m4-1.4.18,1 (options changed)
	help2man-1.47.5 (options changed)

Number of packages to be installed: 1
Number of packages to be reinstalled: 5

The process will require 2 MiB more space.
3 MiB to be downloaded.

Proceed with this action? [y/N]: y
[1/6] Fetching xorg-server-1.18.4_6,1.txz: 100%    1 MiB 184.0kB/s    00:08    
pkg: cached package xorg-server-1.18.4_6,1: size mismatch, fetching from remote
[2/6] Fetching xorg-server-1.18.4_6,1.txz:  18%  272 KiB 180.2kB/s    00:08 ETA

First I’d thought it was just some FreeBSD mirrors were out of sync of each others. This happens quite frequently with Ubuntu mirrors. Usually, we give it a bit of time and the problem will fix itself.

Fix: Fail running Firefox on FreeBSD without D-Bus running

Sun, 11 Feb 2018 17:15:08 +0000

This weekend I replaced Kubuntu 16.04 with FreeBSD 12 on an old HP laptop. I came across with lots of problems, but mainly because I wanted to have some experiences with UEFI and GPT.

Anyway, currently the laptop is running FreeBSD 12-current with i3 as the windows manager. After Firefox was installed, I ran it from the menu (rofi) and nothing appeared. So I ran it from a terminal instead. Here was the output:

Create a FreeBSD install disk with dd on OS X

Fri, 09 Feb 2018 22:23:20 +0000

I need to create a bootable FreeBSD install disk and the downloaded file happened to be on a Mac laptop. Since OS X is based on BSD, it also comes with dd utility.

After a USB is inserted, I need to identify the disk. This can be done using diskutil command:

$ sudo diskutil list
/dev/disk0 (internal):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                         251.0 GB   disk0
   1:                        EFI EFI                     314.6 MB   disk0s1
   2:                 Apple_APFS Container disk1         250.7 GB   disk0s2
/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +250.7 GB   disk1
                                 Physical Store disk0s2
   1:                APFS Volume Macintosh HD            98.6 GB    disk1s1
   2:                APFS Volume Preboot                 21.4 MB    disk1s2
   3:                APFS Volume Recovery                509.8 MB   disk1s3
   4:                APFS Volume VM                      3.2 GB     disk1s4
/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     Apple_partition_scheme                        *2.1 GB     disk2
   1:        Apple_partition_map                         4.1 KB     disk2s1
   2:                  Apple_HFS                         2.4 MB     disk2s2

From the above output, the USB drive is /dev/disk2. Now, I can use dd to copy the image file to the USB drive using the following command:

MySQL server has gone away – how to get it back

Thu, 08 Feb 2018 15:56:47 +0000

Has MySQL/MariaDB server ever run away from you? If it hasn’t, you’re lucky or you’re likely to use PostgreSQL instead.

Today I’m trying to restore a database from backup (database dump) onto a new MariaDB server. This is what happened:

# mysql -u db_user -p db4 &lt; db4-4.4.2_02-08-2018.sql
Enter password:
ERROR 2006 (HY000) at line 354: MySQL server has gone away

The database size is 1.7G, and this should not surprised a database administrator. But it did surprise me because: firstly I’m not a db admin, and secondly I had this issue before just a few weeks ago. So here is a blog post to make sure I won’t forget it for the 3rd time. Basically, I just need to increase the max_allowed_packet size from the default 16MB to something bigger. I chose 128MB.

FreeBSD Recover GTP Table

Sat, 03 Feb 2018 22:30:18 +0000

Recently one of my servers that runs FreeBSD 11.1 keeps hanging on boot. Usually, the 2nd hard reboot will fix it. The root file system on this server is using ZFS and the ZFS pool report it as healthy.

nas:~ # zpool status                                                                                                [136/462]
  pool: zroot                                                                                                                     
 state: ONLINE                                                                                                                    
  scan: scrub repaired 0 in 0h0m with 0 errors on Tue Jan 23 23:54:42 2018                                                        
config:                                                                                                                           
                                                                                                                                  
        NAME        STATE     READ WRITE CKSUM                                                                                    
        zroot       ONLINE       0     0     0                                                                                    
          gpt/zfs0  ONLINE       0     0     0                                                                                    
                                                                                                                                  
errors: No known data errors

So I’ve been reluctant to do anything about it. Until tonight, when I accidentally list the partition of that drive (ada4):

Blacklisting Local Disk from Multipath

Sun, 28 Jan 2018 23:43:03 +0000

In my previous post, I wrote about my quest to identify a disk presented by the Dell server itself. At the end of the post, I mentioned that I should be able to resume with creating a LVM volume on the new disk. LVM stands for Logical Volume Management. There is a good tutorial available at this page if you’re interested in – How To Use LVM To Manage Storage Devices on Ubuntu 16.04.

How to identify a disk on a Dell server

Wed, 24 Jan 2018 13:37:14 +0000

I have a Dell R730 server at work, which connects to a back-end storage with optical fiber cables. In addition, the server itself also has 6 disks. Two of the disks have already been configured as RAID1 and has the operating system installed on it.

Today, I want to configure the remaining 4 disks as RAID10, and setup logical volume on it. The first part was easy. All I had to do was to login to the Integrated Dell Remote Access Controller (iDRAC), and create a new Virtual Disk from the 4 physical disks. The second part is a bit tricky. As the server is connected to the stroage server, it sees a lot of disks.

How to find the motherboard model on Windows 10

Sun, 14 Jan 2018 19:59:50 +0000

To find the motherboard model number on Windows (10), run cmd, and type:

C:\Users\kenno>wmic baseboard get product,Manufacturer,version,serialnumber
Manufacturer                   Product         SerialNumber            Version
Gigabyte Technology Co., Ltd.  Z170N-Gaming 5  To be filled by O.E.M.  x.x

Ref & credit: How to Find Computer and Motherboard Model Serial Number on Windows 10

How to set system locale on Ubuntu 16.04

Sun, 31 Dec 2017 12:03:48 +0000

TLDR; just follow this guide.

At home I run DHCP and DNS servers on Odroid U3, a system on a chip (SoC) computer. This allows me to have lots of control over my home network and most importantly – fun. I also run some web sites and Postgresql databases for testing purposes.

The SoC computer runs Ubuntu 16.04 as the operating system. Recently, the Odroid U3 died.

A coworker also has an SoC, an Odroid XU4. But, he found no use of it so I bought it off him at a very good price. This new SoC will replace the Odroid U3.

Change the urxvt font size on the fly

Sun, 24 Dec 2017 13:42:48 +0000

urxvt or unicode-rxvt is a terminal simulator like Gnome-terminal or Konsole. Recently I’m trying to switch to use i3 (i3-gaps), a tiling windows manager, and urxvt is good compliment to i3.

Unlike Gnome-terminal or Konsole, the font name and size for urxvt are configured in ~/.Xresources. To make change to font size, for example, I’d edit ~/.Xresources, reload it with xrdb ~/.Xresources, and finally close and re-open urxvt itself. Though there is no built-in function to allow changing font size on the fly, urxvt allows us to do this via extensions.

ZFS on Linux is now available for Fedora 27

Tue, 19 Dec 2017 00:34:26 +0000

My main machine at home has been upgraded from Fedora 26 to 27 since the day the 27 was released. Everything has been working great, except the ZFS file system. I’m a ZFS-believer and I store my important files on ZFS-based storage.

For a while there was no repository for Fedora 27 provided by zfsonlinux, until 6 days ago.

I have been using packages provided for Fedora 26 as work around solution. If you’ve been using the ZFS packages for Fedora 26, you can upgrade to the ones for Fedora 27 now.

How to remove a copr repository in Fedora

Mon, 11 Dec 2017 09:56:45 +0000

This is just a quick note to remind myself how to remove a Copr repository. What’s a Copr?

“Copr (Cool Other Package Repo) is a Fedora project to help make building and managing third party package repositories easy.” – https://fedoraproject.org/wiki/Category:Copr.

Why do I want to remove it? One of the Copr repo I added a while back seemed to be no longer working, so I wanted to remove it.

# dnf update --refresh
Failed to synchronize cache for repo 'tcg-themes', disabling.
Last metadata expiration check: 0:00:00 ago on Fri 08 Dec 2017 11:12:45 AM AEDT.
Dependencies resolved.
Nothing to do.
Complete!

To list all repos on Fedora (27):

How to unban IP from PF firewall

Fri, 17 Nov 2017 13:26:49 +0000

This post is probably more relevant to my use case of PF firewall running on FreeBSD 11.1, and I need to remind myself how to unblock an IP from the block list.

Here’s a snippet of what’s in /etc/pf.conf:

table persist

# Don't send rejections. Just drop.
set block-policy drop

# Exempt the loopback interface to prevent services utilizing the
# local loop from being blocked accidentally.
set skip on lo0

# all incoming traffic on external interface is normalized and fragmented
# packets are reassembled.
scrub in on $ext_if all fragment reassemble

# set a default deny policy.
block in log all

# This is a desktop so be permissive in allowing outgoing connections.
pass out quick modulate state

# Enable antispoofing on the external interface
antispoof for $ext_if inet
#antispoof for $ext_if inet6

# block packets that fail a reverse path check. we look up the routing
# table, check to make sure that the outbound is the same as the source
# it came in on. if not, it is probably source address spoofed.
block in from urpf-failed to any

# drop broadcast requests quietly.
block in quick on $ext_if from any to 255.255.255.255

block in log quick on $ext_if inet from  to any

In the pf.conf, the blocked IP table is called sshguard. To list all the blocked IPs, run:

Set the HostName and Computer Name via command line on OS X

Fri, 17 Nov 2017 09:44:26 +0000

Work recently acquired a few MacBook laptops to be used and shared by staff. Though the computing staff is not expected to have immense knowledge about OS X, when things break down we are the first point of contact.

The last time I used a Mac machine extensively was around 2007. Then I switched to Debian and could never look back. Anyway, there must be lot of new things and I’ll try document or post snippets here as I learn new things.

How to list all installed R-packages

Thu, 05 Oct 2017 15:48:55 +0000

I don’t use R, and nor I do know much about it. However, I maintain R’s installation on linux machines at work.

Today, I learned a new trick to list all installed R-packages. Here it is:

ip = as.data.frame(installed.packages()[,c(1,3:4)])
ip = ip[is.na(ip$Priority),1:2,drop=FALSE]
ip

And here is the sample output:

Type 'license()' or 'licence()' for distribution details.

  Natural language support but running in an English locale

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> ip = as.data.frame(installed.packages()[,c(1,3:4)])
> ip = ip[is.na(ip$Priority),1:2,drop=FALSE]
> ip
                  Package   Version
akima               akima    0.5-12
alr3                 alr3     2.0.5
BRugs               BRugs     0.8-6
car                   car     2.1-2
coda                 coda    0.18-1
colorspace     colorspace     1.2-6
DEoptimR         DEoptimR     1.0-5
dichromat       dichromat     2.0-0
digest             digest     0.6.9
distillery     distillery     1.0-2
extRemes         extRemes     2.0-7
fields             fields     8.4-1
...

I don’t have time to explain what each line does. If you’re curious, you can check out using the references below:

Build Docker Client for ARMv8

Sun, 01 Oct 2017 12:51:48 +0000

The other day, after successfully building Docker-ce 17.06.0-dev for Odroid C2 which has ARMv8 CPU, i couldn’t find Docker client. Maybe it was just me not building the Docker engine correctly.

Anyway, after some more times, I also managed building the Docker client for the Odroid C2. It turned out, like many things, it wasn’t that hard after you figured it out. It’s worth to note too that the build instruction on https://github.com/docker/cli is to use Docker container. It didn’t work for me, and I decided to just build the Docker cli locally on the Odroid C2 instead.

Install Grub on GPT

Mon, 25 Sep 2017 16:45:37 +0000

I came across a problem with grub being broken recently on a system running Ubuntu 16.04. This happened after the grub2 package got upgraded. This post will explain how I solved the problem. If you have similar issues, please do not just copy and paste the commands and execute on your machine. First read on, and try to understand it.

Usually, when this happened in the past, we just need to chroot into the system and reinstall grub. On Ubuntu, assuming you’ve chrooted into the system, and the boot disk is /dev/sda, this could be done by running:

Remove trailing whitespace with VIM

Thu, 27 Jul 2017 11:50:49 +0000

Here’s a quick tip on how to get rid of unwanted trailing whitespace using vim.

Let’s say, I have the following code:

Open that file with vim. The following command deletes any trailing white spaces.

:%s/\s\+$//e

Here’s the screenshot of the text after removing the whitespace:

In search, \s finds whitespace (a space or tab). \+ finds one or more occurrences. $ matches the end of line, finally e flag means no error is displayed.

RHCSA’s Prep

Sun, 19 Feb 2017 12:37:13 +0000

At the end of last year, I took a training to prepare for Red Hat Certified System Administrator (RHCSA EX200) exam. Now it’s February and I haven’t taken the exam yet. Even worse, I forgot most of the things I learned during that 3 day training. Well, since I’m being chased to get this exam done ASAP, with a passing grade of course, I think now it’s the best time to start revising the material again. As part as the exam prep, I’m going to post small challenges and solutions.

How to toggle between buffers in Vim with vim-airline

Sun, 29 Jan 2017 20:55:55 +0000

First if you haven’t yet heard about vim-airline plugin, and you’re a Vim user, you really owe it to yourself to check it out.

By default vim-airline displays the opening buffers on the top part of the window.

So how to navigate between those buffers? Well, according to this, it seems those buffers are for visual only. To navigate between them, we can use :bp for previous buffer, and :bn for next buffer. Alternatively, we can use :ls to list all buffers, then navigate to a particular buffer by running :number (substitute number with an actual number).

Changing a User’s Password on FreeBSD

Tue, 10 Jan 2017 23:12:57 +0000

Before getting into how to change a user’s password on FreeBSD, let’s have a quick revision on how that can be done on a Linux system.

As a user we can change the password by typing:

$ passwd
Changing password for user kenno.
Changing password for kenno.
Current password: 
...

Or with a root account, we can change/set the password for another user:

# passwd kenno
Changing password for user kenno.
New password: 
...

How about a FreeBSD? It should be the same way as how it’s done on Linux right? Right? Well, not quite.

FreeBSD 11 Blank Screen After Login via SLiM

Mon, 09 Jan 2017 16:46:23 +0000

After rebooting my FreeBSD 11.0, I wasn’t able to login to Mate desktop manager via SLiM (Login Manager).

I spent sometimes to try to fix it, but failed. I’ll try it again later when I have a bit of free time.

Here’s a quick note of a work around, so I won’t forget what I’ve done.

Disable loading slim on start up by editing /etc/rc.conf and commented out the following line:

Zpool Not Automatically Mounted on Boot on Fedora

Tue, 20 Dec 2016 15:12:40 +0000

I love ZFS, but there is something that has annoyed me for quite sometimes – the zpool doesn’t get automatically mounted on boot. To work around this, I had to login as root and run:

# zpool import tank

to import tank pool before I login with my normal user account.

Well, I finally found a solution. This is what’s written on zfsonlinux/zfs WIFI about Fedora specifically:

Systemd Update:

When upgrading to the zfs-0.6.5.8 release it’s recommended that users manually reset the zfs systemd presets. Failure to do so can result in the pool not automatically importing when the system is rebooted.

របៀបលុបអត្ថបទចម្រៀងចេញពី mp3

Sat, 17 Dec 2016 21:38:44 +0000

ខ្ញុំមានបទចម្រៀង mp3 ពីរឬបី ដែលមានអត្ថបទចម្រៀងភ្ជាប់ជាមួយ (embedded lyric)។ ខ្ញុំចង់លុបអត្ថបទនោះចេញ។

នេះជាវិធីមួយ ដែលអាចសម្រេចបំណងខាងលើ ដោយប្រើកម្មវិធីឈ្មោះ id3v2 នៅលើហ្វេដ័ររ៉ា។ ឧទាហរណ៍ថា ចម្រៀងដែលខ្ញុំចង់លុបអត្ថបទភ្ជាប់នោះ មានឈ្មោះថា “01 love you.mp3” ខំម៉ានដែលយើងត្រូវវាយ ដូចខាងក្រោមនេះ៖

$ id3v2 --remove-frame 'TEXT' 01\ love\ you.mp3

--remove-frame – លុប id3v2 frame
'TEXT'

បើសិនជាយើងមាន mp3 ច្រើនក្នុង directory តែមួយ ហើយយើងចង់លុប ‘TEXT’ frame ចេញ យើងអាចប្រើខំម៉ានដូចនេះ៖

$ for i in *.mp3; do id3v2 -r 'TEXT' $i; done
Deleting Frame TEXT in file 01 love you.mp3 ...
Deleting Frame TEXT in file 02 Ima demo Aitai yo….mp3 ...
Deleting Frame TEXT in file 03 Brand New World.mp3 ...

សូមកត់សំគាល់ថា ក្នុងខំម៉ានខាងលើ ខ្ញុំប្រើ -r ជំនួសអោយ --remove-frame។ អផសុន (options) ទាំងពីរនោះ វាដូចគ្នាទេ៕

Nvidia Driver on Fedora 25

Sat, 17 Dec 2016 16:22:44 +0000

Fedora 25 has Wayland enabled by default. However, if your computer has a (good) Nvidia graphic card and want to make use of it, you’ll need to switch to Xorg and install the Nvidia proprietary driver.

Note that only the Nvidia driver with the version newer than 375.20 works on Fedora 25.

Ref: How do I install the Nvidia driver on Fedora 25?

Install ZFS on Fedora 25 with kernel 4.8.13-300

Thu, 15 Dec 2016 23:08:52 +0000

After I had my Fedora 24 upgraded to 25 on my desktop, ZFS no longer worked. I tried to remove zfs package and reinstalled; it didn’t work.

Here’s how I got it working after trying many things. There could be a different way to fix it, though.

Let’s check the version of the kernel:

[root@sangkae ~]# uname -r
4.8.13-300.fc25.x86_64

Check if spl, zfs are already installed:

[root@sangkae ~]# dnf info spl
Last metadata expiration check: 1:01:18 ago on Thu Dec 15 22:42:25 2016.
Installed Packages
Name        : spl
Arch        : x86_64
Epoch       : 0
Version     : 0.6.5.8
Release     : 1.fc25
Size        : 48 k
Repo        : @System
From repo   : zfs
Summary     : Commands to control the kernel modules
URL         : http://zfsonlinux.org/
License     : GPLv2+
Description : This package contains the commands to verify the SPL
            : kernel modules are functioning properly.

[root@sangkae ~]# dnf info zfs
Last metadata expiration check: 1:01:26 ago on Thu Dec 15 22:42:25 2016.
Installed Packages
Name        : zfs
Arch        : x86_64
Epoch       : 0
Version     : 0.6.5.8
Release     : 1.fc25
Size        : 808 k
Repo        : @System
From repo   : zfs
Summary     : Commands to control the kernel modules and libraries
URL         : http://zfsonlinux.org/
License     : CDDL
Description : This package contains the ZFS command line utilities.

Manually install spl, dkms:

លុបចោលសម្លេងពីឯកសារ MKV

Tue, 15 Nov 2016 22:25:55 +0000

ឥឡូវនេះខែវិច្ឆិកាហើយ ប៉ុន្តែខ្ញុំមិនទាន់បានសរសេរអត្ថបទមួយឡើយ។ អញ្ចឹង គួរតែចាប់ផ្តើមមួយទៅមែនទេ?

ថ្ងៃនេះខ្ញុំចង់ចែករំលេករបៀបលុប audio track ចេញពីឯកសារ MKV ។ MKV ជាប្រភេទមួយនៃហ្វមម៉ាតរបស់ឯកសារ (file format) ដែលយើងអាចខ្ចប់វីដេអូ សម្លេង និងសាប់ថាយថើល (subtitle)។ល។ ខ្ញុំមានឯកសារ MKV ដែលមានសំលេងពីរ ហ៊ីនឌី (Hindi) និងអង់គ្លេស ហើយ ខ្ញុំចង់លុបហ៊ីនឌីចេញ ដោយប្រើកុំព្យូទ័រជាមួយហ្វឺដរ៉ា (Fedora 24)។

ជាដំបូង យើងត្រូវបញ្ចូលប្រូក្រាមមួយជាមុនសិន។

# dnf install mkvtoolnix

ក្រោយពីបញ្ចូលប្រូក្រាមខាងលើ យើងអាចមើលថាតើមានអ្វីខ្លះនៅក្នុងឯកសារ MKV នោះ។

$ mkvmerge -i Sample.mkv
File 'Sample.mkv': container: Matroska
Track ID 0: video (MPEG-4p10/AVC/h.264)
Track ID 1: audio (MP3)
Track ID 2: audio (AAC)
Track ID 3: subtitles (SubRip/SRT)
Attachment ID 1: type 'image/jpeg', size 298984 bytes, file name 'Cover.jpg'

តាមលទ្ធផលខាងលើ យើងឃើញថា ឯកសារនោះមានសម្លេងពីរ Track ID 1 និង Track ID 2។ អ្វីដែលយើងមិនអាចដឹងគឺ តើធ្រាក់មួយណាជាសម្លេងភាសាហ៊ីនឌី? យើងអាចប្រើប្រូក្រាម mplayer:

How extract 7zip file on Linux

Thu, 20 Oct 2016 23:07:49 +0000

This evening I need to extract a file with .7z extension. Guess what? I don’t know how to do that. I probably don’t even have 7zip program installed on my Fedora machine.

Here’s something to remind myself how to get it working.

First let’s find out what package we need to install:

[root@watamem ~]# dnf search 7zip
Last metadata expiration check: 3:14:50 ago on Thu Oct 20 20:39:30 2016.
================ N/S Matched: 7zip ==================
p7zip-plugins.x86_64 : Additional plugins for p7zip
p7zip.x86_64 : Very high compression ratio file archiver
p7zip-gui.x86_64 : 7zG - 7-Zip GUI version

So, it seems we need to install p7zip.

Labeling an XFS Partition

Thu, 29 Sep 2016 11:19:09 +0000

Let’s say I have a partition as /dev/sdc1 formatted using XFS file system, and I want to give a label to it as externo. Here is one way to do it:

# xfs_admin -L externo /dev/sdc1
writing all SBs
new label = "externo"

To read the label:

# xfs_admin -l /dev/sdc1
label = "externo"

Reference:

HowTo Rename a XFS-Filesystem (label it)

FreeBSD upgrade pool zroot

Tue, 27 Sep 2016 21:09:39 +0000

Today I successfully upgraded my FreeBSD home nas server from 10.3 to 11.0. This is the final release of version 11.0, though the official announcement is expected to be made on September 28.

After the system upgrade, I need to also upgrade the 2 zpools (tank and zroot) so they can have new features. Upgrading tank was easy, all I needed to do was running this command:

# zpool upgrade tank
This system supports ZFS pool feature flags.

Enabled the following features on 'tank':
  sha512
  skein

For zroot, in addition to running the above command (by replacing the actually zpool name to zroot), I also need to update the boot code.

Perl IO::Socket::INET6::sockaddr_in6 redefined error

Wed, 14 Sep 2016 16:55:56 +0000

Yesterday I installed spamassassin package on a server running RHEL 6.8. Then this morning, I received an email alert with the following message:

Subroutine IO::Socket::INET6::sockaddr_in6 redefined at /usr/share/perl5/Exporter.pm line 67.
 at /usr/share/perl5/IO/Socket/INET6.pm line 21.
Subroutine IO::Socket::INET6::sockaddr_in6 redefined at /usr/share/perl5/Exporter.pm line 67.
 at /usr/share/perl5/IO/Socket/INET6.pm line 21.
Subroutine IO::Socket::INET6::sockaddr_in6 redefined at /usr/share/perl5/Exporter.pm line 67.
 at /usr/share/perl5/IO/Socket/INET6.pm line 21.
Subroutine IO::Socket::INET6::sockaddr_in6 redefined at /usr/share/perl5/Exporter.pm line 67.
 at /usr/share/perl5/IO/Socket/INET6.pm line 21.

This seems to be a bug exists in an old version of IO::Socket::INET6. Upgrading this package should fix the problem:

Warning: Use of "localtime" without parentheses is ambiguous

Wed, 14 Sep 2016 15:11:23 +0000

While looking at the log produced by Request Tracker (RT) 4.2.12, I noticed there was a warning message about using “localtime” without parentheses.

Here’s the actual error message:

[warning]: Warning: Use of "localtime" without parentheses is ambiguous 
at /opt/rt4/sbin/../lib/RT/Interface/Email.pm line 526.

The solution which I found from here, fixed the problem:

On line 526 of file /opt/rt4/sbin/../lib/RT/Interface/Email.pm, replace:

localtime with localtime().

Thanks to the chap who posted the solution.

Losing ZFS storage for Docker

Sun, 11 Sep 2016 01:09:40 +0000

I use ZFS as a storage driver for docker engine running on my machine. Today after my machine rebooted from a crash, yes Linux system crashes too, I notice that all my docker images and containers disappeared.

~ ❯❯❯ docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
~ ❯❯❯ docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

First thing came to my mind was “did I accidentally destroy docker zfs data set last night?”

Make Gnome Title Bar Small Again

Fri, 02 Sep 2016 10:15:05 +0000

Sometimes in life, greater is not always better. Here’s a config which I used to make the Gnome 3 title bar smaller.

Create a file in ~/.config/gtk-3.0/gtk.css:

headerbar.default-decoration {
    padding-top: 3px;
    padding-bottom: 3px;
    min-height: 0px;
    font-size: 0.7em;
}

headerbar.default-decoration button.titlebutton {
    padding: 0px;
    min-height: 0px;
}

Here’s how the title bar looks like before and after applying the custom css file:

Install Hack font on FreeBSD 10

Thu, 25 Aug 2016 16:57:20 +0000

FreeBSD 10 comes with a pkgng package manager which allows to install binary packages faster and easier.

Unfortunately, there is no binary package available for hack-font for FreeBSD 10. What is hack-font? It’s a very good font which looks very good for source code.

Here’s how to install it from source.

Check /usr/ports/x11-fonts to see if there is a directory named hack-font. If not, you might need to download or update the ports first. If you don’t have ports installed at all, do this:

Puppetserver failed to start after upgrading to 2.5.0

Mon, 15 Aug 2016 11:24:55 +0000

I upraded puppetserver from 2.4.0 to 2.5.0 on a server running Centos 6.8. Then, puppetserver no longer starts.

The log (I think it was puppetsrver-daemon.log) said:

Exception in thread "main" java.lang.IllegalArgumentException: Specified bootstrap config file does not exist: '/etc/puppetlabs/puppetserver/bootstrap.cfg'

As the error reported, /etc/puppetlabs/puppetserver/bootstrap.cfg was not there. The disappearance must have happened during the puppetserver upgrade. I can confirm this by looking at my backup directory and finding the boostrap.cfg file there: /srv/backup/etc/puppetlabs/puppetserver/bootstrap.cfg.

How to remove a user password

Sun, 07 Aug 2016 22:38:20 +0000

Sure, you Linux gurus must be laughing at me to see this post. However, this is my 2nd time needing to remove a user’s password and I had to Google for it! So here is just a quick tip to mind your truly:

# passwd -d your_username

In case you’re wondering why I need to remove a password for an account, it’s for my 4 year old daughter who enjoys playing supertuxcart. She wants to have her own user account on a Fedora 24 box without a password.

បង្កើត RSS feeds ពី SoundCloud និង iTunes urls

Sun, 31 Jul 2016 00:25:56 +0000

ខ្ញុំចូលចិត្តស្តាប់ ផត់ខាស់ណាស់ ពីព្រោះវាមានអត្ថប្រយោជន៍ជាច្រើន។ តើផត់ខាសបានការអ្វីខ្លះ? បើសិនជាអ្នកចង់ដឹង សូមសួរក្នុងខំម៉ិនខាងក្រោម។

ថ្ងៃនេះ ខ្មុំចង់ប្រាប់របៀបបង្កើត RSS feeds ពីផត់ខាស់ដែលត្រូវការ អាយធូនដើម្បីស្តាប់បាន។ ជាមួយ RSS feeds យើងអាចប្រើកម្មវិធីផ្សេងៗដូចជា អាម៉ារ៉ុក។

មុនដំបូង យើងត្រូវចំលងលិង អាយធូន ហើយចូលទៅ http://getrssfeed.com/ និងបិទលិងនោះ។ វិបសាយ getrssfeed.com និងផ្តល់លិងថ្មី ដែលជា RSS feed.

វិធីខាងលើអាចប្រើជាមួយ SoundCloud urls ផងដែរ៕

Resizing an LVM logical volume

Wed, 20 Jul 2016 16:11:51 +0000

One of the logical volumes on my desktop is running out of space. I want to add 200GB to that volume. Here is one way to achieve this task.

First a bit of warning. Don’t, or never, just copy and paste what you see here if you want to apply it to your own system. You may accidentally destroy your precious data.

# lvs
  LV      VG     Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  backup  data   -wi-ao---- 200.00g                                                    
  scratch data   -wi-ao----   1.00t                                                    
  home    system -wi-ao----  90.00g                                                    
  root    system -wi-ao---- 100.00g                                                    
  swap    system -wi-ao----  16.00g                                                    
  tmp     system -wi-a-----   4.00g                                                    
  var     system -wi-ao----  20.00g

Let’s check the available disk space of volume groups we can use:

Fix corrupted GPT on FreeBSD

Thu, 14 Jul 2016 18:40:15 +0000

One of the disks in my FreeBSD server reported an issue:

Jul 14 18:00:56 nas kernel: GEOM: da0: the primary GPT table is corrupt or invalid.
Jul 14 18:00:56 nas kernel: GEOM: da0: using the secondary instead -- recovery strongly advised.
Jul 14 18:00:56 nas kernel: GEOM: diskid/DISK-67304734999999999999: the primary GPT table is corrupt or invalid.
Jul 14 18:00:56 nas kernel: GEOM: diskid/DISK-67304734999999999999: using the secondary instead -- recovery strongly advised.

To verify it, first I used gdisk command:

How to convert vdi to qcow2 image

Sun, 03 Jul 2016 20:22:40 +0000

vdi file is a type of disk image used by VirtualBox. qcow2, on the other hand, is the format of disk image used by KVM.

Recently, I want to move some existing virtual machines running on VirtualBox to KVM. To do that I need to convert the disk image from vdi to qcow2. Here’s one way to achieve that:

# qemu-img convert -f vdi -O qcow2 disk.vdi disk.qcow2

Ref: How to convert VirtualBox vid to KVM qcow2

FreeBSD git fatal: Unable to find remote helper for 'https'

Fri, 01 Jul 2016 23:15:03 +0000

I just found out that git is not fully functional on my FreeBSD (11) box. It was installed from port (using portmaster git). I can clone a repo using SSH key, but not with HTTPS.

I’m not quite sure if it’s always been this way. Here is how to fix it:

Reinstall curl

# pkg remove curl
# portmaster curl

Reinstall git

# pkg remove git
# portmaster git

Why did I install git from port? Well, ‘cuz there is no binary package for FreeBSD 11 arm, which runs on my Raspberry Pi B+.

grep: error while loading shared libraries: libpcre.so.0

Fri, 01 Jul 2016 14:14:13 +0000

I have a server running CentOS 6 successfully upgraded to CentOS 7.

The only problem I encountered so far is that ‘grep’ doesn’t work.

[root@zilla ~]# grep
grep: error while loading shared libraries: libpcre.so.0: cannot open shared object file: No such file or directory

[root@zilla ~]# ldd /usr/bin/grep
        linux-vdso.so.1 =>  (0x00007ffc0b639000)
        libpcre.so.0 => not found
        libc.so.6 => /lib64/libc.so.6 (0x00007f6be1c6c000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f6be2038000)

First thing I tried was to reinstall pcre package which provides libpcre.so*. It still didn’t work. Fortunately, someone has posted a solution as the following:

Create bootable USB Fedora 24

Mon, 27 Jun 2016 10:21:29 +0000

Every time there is a new release of Linux distro, I need to create a bootable USB. And, I forgot how I did it last time. So, I tried by using the “Startup Disk Creator” program installed on my Ubuntu workstation, only to find out that it didn’t even work.

After a while I remember, it was just a matter of using dd command to copy the ISO image to the USB.

How to remove a newline at end of file

Thu, 09 Jun 2016 16:21:06 +0000

Those who know me know that I don’t like Perl. Sometimes in life the thing you don’t like could be best tool/friend.

I need to remove a newline character from a text file: layouts/partials/pagination.html.

$ git diff layouts/partials/pagination.html
diff --git a/layouts/partials/pagination.html b/layouts/partials/pagination.html
index 00c1124..d8dd981 100644
--- a/layouts/partials/pagination.html
+++ b/layouts/partials/pagination.html
@@ -15,4 +15,4 @@
         </span>
         {{ end }}
     {{ end }}
-</nav>
\ No newline at end of file
+</nav>

The easiest way to do this is to run the following command:

Fedora 23/24 gcc: error: /usr/lib/rpm/redhat/redhat-hardened-cc1

Sun, 15 May 2016 17:39:56 +0000

While updating Ansible pip package on Fedora 24 today, I got the following error message

gcc: error: /usr/lib/rpm/redhat/redhat-hardened-cc1: No such file or directory

I believe I came across this problem before when I installed a ruby gem on Centos 6 a short while back. Unfortunately, I already forgot how I’d solved it. So here’s a note to remind myself or anyone who’s having the same issue.

We need to install a package called: redhat-rpm-config.

Installing Pip with Python 3.5 on FreeBSD

Fri, 06 May 2016 16:09:41 +0000

Here is a quick note serves as a self-reminder on how to get pip working or installed on FreeBSD 10.3.

First, ensure that Python 3 package is installed. Python 3 is provided by python35 package.

# pkg install python35

However, there is no package for pip, at least at the time of this writing, on FreeBSD. To have it installed, run the following command:

# python3.5 -m ensurepip

We should as well update pip to new version:

How to renew DHCP lease with NetworkManager

Thu, 17 Mar 2016 22:24:25 +0000

Traditionally, we use dhclient to release and renew DHCP lease on Linux. It probably still work with modern Linux distros nowadays. However, most distros come with NetworkManager which provides nmcli command line interface to manage networking. Here’s how to renew DHCP lease using nmcli performing on my machine. Your output when running these commands could be different.

First, let’s list the connections managed by NetworkManager.

# nmcli con
NAME                UUID                                  TYPE            DEVICE     
virbr0              2c2c7c4f-15e9-439b-be1d-e1d0131fb41c  bridge          virbr0     
Wired connection 1  5c9000c5-2635-4b09-90d7-71c3783c6626  802-3-ethernet  enp0s25    
enp0s25             70ee0b94-8341-46ec-953d-f2c3ca34285a  802-3-ethernet  --         
virbr0-nic          aafaa95e-6ced-4ea9-bd4f-7c8d10fb51b6  generic         virbr0-nic

Next, we can find out the current IP associated with enp0s25 by running command:

របៀបប្តូរ time zone ពីខំម៉ានឡាញក្នុងអ៊ូប៊ុនធូ

Fri, 11 Mar 2016 23:32:24 +0000

ថ្ងៃនេះ ខ្ញុំបានទទួល Odroid-C2 ដែលបានទិញពី Hardkernel កាលពីអាទិត្យមុន។ OS ដែលអាចដើរលើវាបាន ក្នុងពេលនេះ មានតែ Ubuntu Mate 16.04 LTS ដែលជាបេតា នៅឡើយ។

Time zone ដែលមានស្រាប់ជាដើមគឺ EST (American Eastern Standard Time)។ ខ្ញុំត្រូវការ AEST (Australian Eastern Standard Time) ព្រោះខ្ញុំនៅស៊ីដនី។ នេះជាខំម៉ានដែលអាចប្តូរ Time zone បាន ដោយវាយ ពី ធើរមិណល់។

មុនដំបូង ឆែកមើលមុនសិន៖

odroid64:~# date
Fri Mar 11 08:13:04 EST 2016

ប្រើខំមាន នេះដើម្បីប្តូរ time zone៖

odroid64:~# dpkg-reconfigure tzdata

ជ្រើសយកប្រទេស រួចទីក្រុង។ នេះជាលទ្ធផល៖

Current default time zone: 'Australia/Sydney'
Local time is now:      Sat Mar 12 00:13:57 AEDT 2016.
Universal Time is now:  Fri Mar 11 13:13:57 UTC 2016.

Reference:

Fedora 23: Ansible util.am_i_root():NameError: global name 'util' is not defined

Sun, 28 Feb 2016 13:49:14 +0000

If you see a similar error message as the following when running Ansible on a Fedora 23 machines, there is an easy fix.

It is very likely that a package “python2-dnf” is missing. This package is required for Python script to interact with DNF package manager.

There is a good article available at fedoramagazine.org about running Ansible on Fedora 23. (I only found this later, and it’s very informative.)

Mouse not working in Xorg on FreeBSD

Fri, 19 Feb 2016 09:45:06 +0000

After installing Mate desktop environment on a fresh FreeBSD 10.2 box, mouse was not working. This is what I have in my /etc/rc.conf:

...
moused_enable="YES"
hald_enable="YES"
dbus_enable="YES"

Some suggests that the order of hald and dbus to be swapped around. I tried that, and it still didn’t work.

A bit of more Googlings, I found out a working solution [1]. I need to install: xf86-input-mouse.

Here’s how I did it:

# portmaster x11/drivers/xf86-input-mouse

And that was all required. If your keyboard is not working in Xorg, you might want to also install xf86-input-keyboard.

Upgrading STM32F4-Discovery Firmware on Linux

Mon, 25 Jan 2016 14:18:02 +0000

Not too long ago, upgrading firmware on STM32F4-Discovery board required it to be performed on a Windows machine. That annoyed the heck a lot of people, myself included.

There’s a very good news for Linux and Mac users. Now, you can do it from your favorite OSes. Since I’m so excited about this, here’s a short article on how to do just that.

First download “STSW-LINK007” from <www.st.com/web/en/catalog/tools/PF260217>. At the time of this writing the file is called: stsw-link007.zip.

PostgreSQL: Drop a database which has a hyphen in name

Fri, 22 Jan 2016 13:13:35 +0000

Normally to drop a database in PostgreSQL, we can just type:

DROP DATABASE database;

Here’s a list of my current databases:

postgres=# \l
                                   List of databases
    Name     |   Owner   | Encoding |   Collate   |    Ctype    |   Access privileges   
-------------+-----------+----------+-------------+-------------+-----------------------
 dashboard   | dashboard | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
 postgres    | postgres  | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
 postgres-db | postgres  | UTF8     | en_US.UTF8  | en_US.UTF8  | 
 puppetdb    | puppetdb  | UTF8     | en_US.UTF8  | en_US.UTF8  | 
 template0   | postgres  | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +
             |           |          |             |             | postgres=CTc/postgres
 template1   | postgres  | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +
             |           |          |             |             | postgres=CTc/postgres
(6 rows)

I want to drop a database named postgres-db. So, let’s try to drop it:

Docker with OverlayFS on Ubuntu 15.10

Sat, 26 Dec 2015 00:08:28 +0000

As of today, the default storage for Docker on (K)Ubuntu 15.10 is AUFS. I want to switch it to OverlayFS. Personally, I’m still new to Docker, but I did hear that OverlayFS is better than AUFS. You can read more about OverlayFS here.

Anyway, the purpose of this post is how to switch OverlayFS and avoid head-scratching.

On Ubuntu 15.10 (wily), one can start/stop services either using Upstart or systemd. Since I want to get more accustomed to using systemd, I’ve been trying to use it anywhere possible. For example, here’s the command to start docker:

Puppet service resource provider

Wed, 16 Dec 2015 15:18:13 +0000

Well, first of all I think the title of this post won’t entirely reflect its content. However, I need to go ahead and post this now.

At work, We’ve been having issues with cups service not running on some Kubuntu 14.04 desktops. This should not happen since even if cups service is dead, we have Puppet agent running on each machine

to check and make sure that ‘cups’ is running else will be automatically restarted.

ZFS zpool upgrade

Mon, 14 Dec 2015 00:56:26 +0000

I’m running ZFS on Fedora 23 and I notice that there’re new features which can be enabled in the existing pool.

# zpool status
  pool: tank
 state: ONLINE
status: Some supported features are not enabled on the pool. The pool can
        still be used, but some features are unavailable.
action: Enable all features using 'zpool upgrade'. Once this is done,
        the pool may no longer be accessible by software that does not support
        the features. See zpool-features(5) for details.
  scan: none requested
config:

        NAME        STATE     READ WRITE CKSUM
        tank        ONLINE       0     0     0
          raidz1-0  ONLINE       0     0     0
            sdb     ONLINE       0     0     0
            sdc     ONLINE       0     0     0

errors: No known data errors

Get the ZFS version for tank’s pool:

Copy RaspBSD image to micro SD card

Wed, 02 Dec 2015 22:30:33 +0000

The RaspBSD image for Raspberry Pi can be found at http://raspbsd.org/raspberrypi.html.

After it’s been downloaded, we need to copy it to a microSD card. Before we can do that, we need to find out the device name represents the microSD card. One way to find out is to plug the card in, and check the newest messages of dmesg.

$ dmesg
...
[282430.689656] mmc0: new SDHC card at address aaaa
[282430.691039] mmcblk0: mmc0:aaaa SU08G 7.40 GiB 
[282430.711060] mmcblk0: p1 p2

In my case, using Ubuntu 15.10, the card is detected as mmcblk0.

ERROR: could not insert ‘nvidia_352’: Unknown symbol in module, or unknown parameter (see dmesg)

Tue, 01 Dec 2015 13:15:02 +0000

This is my third time having problem installing Nvidia drivers on Ubuntu (14.04). What’s worse is that I could not remember how I fixed them last time.

Hope this blog post will prevent me from pulling my hair out for the 4th time.

So, I installed Nvidia driver as usual:

# apt-get install nvidia_352

After it’s finished, I tried to load the module:

# modprobe nvidia
modprobe: ERROR: could not insert 'nvidia_352': Unknown symbol in module, or unknown parameter (see dmesg)

Well, it turned out that I need to also install another linux-image package: linux-image-extra-3.13.0-70-generic. If you try to install this package on your machine, ensure that you match the version of the kernel too; i.e. 3.13.0-70 in my case.

How to get IP of guest OS in VirtualBox

Wed, 11 Nov 2015 09:21:18 +0000

After upgrading my VM running Fedora 23 beta to the release version, Gnome Desktop Manager (GDM) no longer started again. This is the same issue with newer version of xorg-x11-*, and it’s not yet supported by VirtualBox 5.0.

I previously posted a quick fix by downgrading xorg-x11-* packages. To do that, I need to ssh into the VM.

Here’s how we can find the IP address of running VMs.

Let’s list the VMs available:

Changing MongoDB storage engine from Mmapv1 to WiredTiger

Tue, 03 Nov 2015 09:03:24 +0000

Changing the storage engine for a standalone MongoDB server from Mmapv1 to WiredTiger is relatively painless.

Here’s how I did it.

Backup the database
```
mongodump --out /srv/backup/mongodb
```
Stop monbodb service
```
service mongodb stop
```

Update mongodb.conf. Here’s my /etc/mongodb.conf file:

# mongod.conf

storage:
  dbPath: "/var/lib/mongo" 
  engine: wiredTiger
  wiredTiger:
    engineConfig:
      cacheSizeGB: 1
      statisticsLogDelaySecs: 0
      journalCompressor: snappy
      directoryForIndexes: false
    collectionConfig:
      blockCompressor: snappy
    indexConfig:
      prefixCompression: true

systemLog:
  verbosity: 1
  path: "/var/log/mongodb/mongod.log" 
  logAppend: true
  logRotate: reopen
  destination: file
  timeStampFormat: iso8601-utc

processManagement:
  fork: true
  pidFilePath: "/var/run/mongodb/mongod.pid" 

net:
  bindIp: 127.0.0.1
  port: 27017
  wireObjectCheck: false
  unixDomainSocket:
    enabled: true

Start monbodb service

GDM Doesn’t Start on Fedora 23 Beta and VirtualBox

Tue, 27 Oct 2015 16:08:16 +0000

I just finished upgrading Fedora 22 to Fedora 23 Beta and upon rebooting, gdm no longer started. I tried to reinstall the VirtualBox Guest Additions; unfortunately it still didn’t fix.

To cut the story short, someone has given a working tip at this forum. The solution is to downgrade xorg-x11-server-Xorg package.

# dnf --showduplicates --allowerasing --releasever=22 downgrade xorg-x11-server-Xorg
# mount /dev/cdrom /mnt; cd /mnt
# ./VBoxLinuxAdditions.run
# reboot

After rebooting, I was able to login again.

Kinetis Design Studio crashes on Kubuntu 14.04

Mon, 03 Aug 2015 12:01:24 +0000

On Kubuntu 14.04, Kinetis Design Studio (KDS) could be started, but when I tried to create a new project, it’d crash with the following message displayed in the terminal:

$ kinetis-design-studio 
java: /build/buildd/gtk2-engines-oxygen-1.4.5/src/animations/oxygencomboboxdata.cpp:87: void Oxygen::ComboBoxData::setButton(GtkWidget*): Assertion `!_button._widget' failed.

KDS is a Eclipse-based IDE. So I suspect the issue is related to Eclipse IDE itself. (I can’t confirm this as I’m not running the Eclipse IDE on this machine. I know I could have just downloaded and test it; but I don’t have time.)

Updating Kinetis Design Studio on Linux

Tue, 28 Jul 2015 11:22:38 +0000

For Linux users who want to update Kinetis Design Studio (DKS), if you launch KDS as a non-privileged user, you’d have to relaunch KDS with sudo for update to go ahead.

$ sudo /opt/Freescale/KDS_3.0.0/eclipse/kinetis-design-studio

Then to update it, just click on Help -> Check for Updates from the menu.

PF firewall rule for DNS server

Thu, 09 Jul 2015 21:06:27 +0000

A reminder to readers, most of these blog posts are to remind me what I have done or fixed some problems. What works for me may not work for you. Most of the time, they aren’t even the best practice.

Here’s a snippet of the PF firewall rule on my FreeBSD box which acts as a DNS server. Basically, the firewall opens up UDP port 53 to allow LAN access it.

Remove a file/directory starting with dash/hyphen

Tue, 07 Jul 2015 21:15:12 +0000

I just noticed that in the /root directory, there exists a directory with its name starting with a dash: -p in my FreeBSD box.

root@raspbsd:~ # ls -l
total 144
drwxr-xr-x  2 root  wheel    512 May  5 18:26 -p
drwxr-xr-x  2 root  wheel    512 May  5 20:45 .byobu
drwxr-xr-x  3 root  wheel    512 May  5 20:45 .cache
-rw-r--r--  2 root  wheel    959 Jan 23 00:59 .cshrc

As much as I wanted to get rid of it, I was curious to find out what’s inside that directory.

ISC Dhcpd Duplicate UID Lease

Thu, 25 Jun 2015 14:10:51 +0000

Someone asked this question in one of his blog posts:

Ever see this?

dhcpd: uid lease 192.168.1.150 for client xx:xx:xx:xx:xx:xx is duplicate on 192.168.1/24

Yes, I’m seeing something like that now in the my dhdcp logs. Here is the actual message:

DHCPREQUEST for 192.168.1.109 from 08:00:27:6e:61:b8 via eth0
DHCPACK on 192.168.1.109 to 08:00:27:6e:61:b8 via eth0
DHCPINFORM from 192.168.1.109 via eth0
DHCPACK to 192.168.1.109 (08:00:27:6e:61:b8) via eth0
uid lease 192.168.1.224 for client 08:00:27:6e:61:b8 is duplicate on 192.168.1.0/24
DHCPREQUEST for 192.168.1.109 from 08:00:27:6e:61:b8 via eth0
DHCPACK on 192.168.1.109 to 08:00:27:6e:61:b8 via eth0

I think I know why this happened. Basically, the machine with MAC address of ’08:00:27:6e:61:b8′ used to have grab an IP address

PySpark takeOrdered example

Wed, 24 Jun 2015 20:54:04 +0000

Sort by keys (ascending):

RDD.takeOrdered(5, key = lambda x: x[0])

Sort by keys (descending):

RDD.takeOrdered(5, key = lambda x: -x[0])

Sort by values (ascending):

RDD.takeOrdered(5, key = lambda x: x[1])

Sort by values (descending):

RDD.takeOrdered(5, key = lambda x: -x[1])

Credit: http://stackoverflow.com/questions/30787635/takeordered-descending-pyspark

YUM what provides this file, huh?

Wed, 24 Jun 2015 17:08:20 +0000

This post is primarily written to remind myself, an Ubuntu user, to figure out how to find what RPM package provides a file — for example a header file.

Today, I’m trying to compile and install R 3.1.3 on CentOS 6 from source code. This R installation is one of the requirements to install Tessera stack. The instruction from the installation page is:

sudo yum install blas blas-devel lapack lapack-devel
wget http://cran.r-project.org/src/base/R-3/R-3.1.3.tar.gz
tar zxvf R-3.1.3.tar.gz
cd R-3.1.3
./configure --with-blas --with-lapack --with-x --enable-R-shlib
make
sudo make install

Unfortunately, the process failed with ./configure with the complain about missing readline library. To fix it, I had to install readline-devel package.

Install PostgreSQL server on Raspberry Pi from FreeBSD port

Thu, 18 Jun 2015 20:04:40 +0000

Before I wrote this blog post, I had thought there was no binary package for PostgreSQL server for FreeBSD 11 running on Raspberry Pi. Hmm… how wrong I was! I just wasted the whole night compiling Postgres from source. DOH!

Anyhow, here’s the step I took to do it. If you’re familiar with FreeBSD, there’s nothing new here. But, I only use FreeBSD once in awhile, and so I tend to forget a lot what I do.

Disable puppet-lint class inheriting from params class

Thu, 18 Jun 2015 11:17:51 +0000

I normally use Vim to edit Puppet modules and manifests codes. However, recently I just found out about Atom editor, and quite like it. Out of the box, Atom supports many programming languages by providing syntax highlight. There are hundreds of Packages available which provide more functionalities such as make Atom to behave like a Vi editor, support Puppet codes, etc.

As mentioned earlier, Atom provides syntax highlighting for various programming languages; well except Puppet. So we need to manually install a package that fills that requirement: language-puppet. I also suggest that you additionally install linter and linter-puppet packages.

ការបញ្ចូល git ក្នុង Raspberry Pi ដើរ FreeBSD 11

Fri, 29 May 2015 21:36:56 +0000

ដោយសារពុំមាន កញ្ចប់បាយនារី (binary package) នៃ git យើងត្រូវបញ្ចូល gitពីសោះខូត ដូចខាងក្រោម៖

# cd /usr/ports/devel/git
# make install clean

សង្ឃឹមថាថ្ងៃក្រោយឆាប់ៗ កញ្ចប់បាយនារី នឹងបានបង្កើតឡើង ព្រោះខំផាយពី សោះខូតយើតណាស់ ជាពិសេសពេលខំផាយវាលើ រ៉ាស់ប៊ែរីផាយ។

របៀបលុបណូតចេញពី Puppet master

Fri, 22 May 2015 10:24:52 +0000

នៅកន្លែងធ្វើការ ខ្ញុំប្រើ Puppet ដើម្បីគ្រប់គ្រង ម៉ាស៊ីនជាច្រើន។ ជួនកាលខ្ញុំត្រូវការលុបម៉ាស៊ីនចេញ ពី Puppet master ដោយសារម៉ាស៊ីននោះលែងត្រូវការហើយ។ នេះជាជំហានដែលត្រូវធ្វើ៖

១. លុបមាស៊ីន ឬ ណូតនោះពី puppet dashboard

២. លុប certificate របស់ម៉ាស៊ីននោះចេញពី puppet master ដោយវាយ ខំម៉ាន

# puppet cert clean node123.example.com

៣. ដោយសារខ្ញុំប្រើ PuppetDB ខ្ញុំត្រូវលុប ណូតនោះ ចេញពី PuppetDB ដែរ

# puppet node deactivate node123.example.com

ខ្ញុំសរសេរ អត្ថបទនេះ ដើម្បីរំលឹកខ្លួនឯងពេលខ្ញុំត្រូវការធ្វើវាម្តងទៀត។ បើសិនជាលោកអ្នក មានសំណូមពរ ឬសំណួរទាក់ទងនឹង ការប្រើប្រាស់ Puppet អាចសួរខ្ញុំបាន៕

R-tip: List installed R packages

Wed, 29 Apr 2015 17:04:03 +0000

> rownames(installed.packages())
 [1] "bitops"     "manipulate" "RCurl"      "rgl"        "rstudio"   
 [6] "scrapeR"    "XML"        "base"       "boot"       "class"     
[11] "cluster"    "codetools"  "compiler"   "datasets"   "foreign"   
[16] "graphics"   "grDevices"  "grid"       "KernSmooth" "lattice"   
[21] "MASS"       "Matrix"     "methods"    "mgcv"       "nlme"      
[26] "nnet"       "parallel"   "rpart"      "spatial"    "splines"   
[31] "stats"      "stats4"     "survival"   "tcltk"      "tools"     
[36] "utils"     
>

Fixing “Starting version 219” bug in Kubuntu 15.04 Beta

Fri, 27 Mar 2015 14:52:18 +0000

After restarting my laptop which run Kubuntu 15.04 beta, it got stuck at a black screen with a message: Starting version 219. I tried to reboot it a few times, and it always displayed the same message. Fortunately, I found a solution from this page which fixed the problem.

Here’s a recap on how to do it.

When you see the above message, hit Ctrl + Alt + F2
Run sudo systemctl enable sddm.service -f

Installing Code Composer Studio 6 on Ubuntu 14.10 (64-bit)

Tue, 03 Mar 2015 22:48:55 +0000

As of today, Code Composer Studio (ccs) 6 is only available for 32-bit Linux platform. The good news is that it can be installed on a 64-bit version of Ubuntu and Fedora.

In this blog post, I’m going to show a few issues I came across and how to fix them on Ubuntu 14.10 64-bit.

Issue 1:

After the installation, when I ran the ccs, it produces some warning and error messages then quit.

Mounting qcow2 VM disk images

Thu, 19 Feb 2015 10:05:12 +0000

From time to time, after applying Windows updates on my Windows 7 kvm-based virtual machine, the machine won’t boot after restarting. In the past, I was lucky to be able to fix it.

Last night, I could not say the same thing. Instead of stressing out losing my hair on how to get it working again, it’s decided to just restore the whole Windows image. First, I need to get some updated data from it though.

Good permission for /tmp

Mon, 16 Feb 2015 12:44:18 +0000

I have been having issues getting X2Go running on a CentOS 6.5 box. It took me a while to figure out that the problem laid with the permission of /tmp directory. I’ll write how to solve the X2Go problem in another post.

The recommended permission for /tmp is 1777. Notice that the forwarding ‘1’ is the sticky bit which only allows the owner of the file within /tmp (or the root user) to delete/rename the file.

Pololu A-Star 32U4 Mini on Ubuntu

Sat, 13 Dec 2014 23:12:40 +0000

Recently I received a A-Star 32U4 mini board from Pololu, which I’d bought during the Black Friday for just $6.

Since this mico-controller board shares many similarities with Arduino Leonardo, I thought I could just upload the program using Arduino IDE by selecting Arduino Leonardo as the board type.

Unfortunately, that did not work even after I tried resetting the board as suggested in the following the error message logged by Arduino IDE in the console:

Updating Nexus 7 to Lollipop using sideload

Sat, 13 Dec 2014 22:16:57 +0000

This post is a note to remind myself how to manually flash Android firmware on a Nexus device.

Step 1, download the firmware to your computer. I downloaded Android 5 from:

http://www.droid-life.com/2014/11/13/download-android-5-0-ota-update-nexus-5-7-10-4/

Step 2, connect Nexus 7 to the computer. Mine runs Ubuntu 14.10, and I already downloaded Android SDK.

Make sure that “Developer Options” is enabled. If it’s not, go to Settings -> About tablet. Then click on “Build Number” 7 times.

Gtk-Message: Failed to load module "overlay-scrollbar"

Tue, 09 Dec 2014 22:12:58 +0000

On Ubuntu distro, if you see the error message below in console whenever you run a Gnome-based applications, chances are you had overlay-scrollbar package previously installed but now removed. In addition, the configuration file which came with that package remained on your system.

Gtk-Message: Failed to load module "overlay-scrollbar"

To verify this, we can run the command:

$ dpkg -l overlay-scrollbar
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                         Version             Architecture        Description
+++-============================-===================-===================-================
rc  overlay-scrollbar            0.2.16+r359+14.04.2 all                 Scrollbar overlay

rc : remove but config file still presents.

vim-youcompleteme

Fri, 05 Dec 2014 13:32:14 +0000

I need to setup vim-youcompleteme to get real-time completion for write Golang code.

Assuming that this part has been completed first:

$ cd ~/.vim/bundle
$ git clone https://github.com/fatih/vim-go.github

Here’s how vim-youcompleteme is installed/enabled on Ubuntu 14.04:

$ sudo apt-get install vim-addon-manager vim-youcompleteme
$ vam install youcompleteme

Note: vam is short for the vim-addon-manager.

Reference:

http://blog.gopheracademy.com/vimgo-development-environment/

Android Studio Cannot Resolve Symbol R

Tue, 25 Nov 2014 15:36:52 +0000

I just got this problem today when I opened an Android project with Android Studio. Basically, anywhere there’s a reference to R, for example R.layout.footer_view, Android Studio will complain that it cannot resolve symbol R.

The fix is surprisingly easy. All I need to do was running Gradle clean and Gradle build.

Ref: http://stackoverflow.com/questions/17054000/cannot-resolve-symbol-r-android-studio

Installing Linux Mint 17 on Virtualbox

Tue, 21 Oct 2014 10:37:40 +0000

You may or may not have problem installing Linux Mint 17 on VirtualBox depending on the setting of your Virtualbox VM. I had this problem and took me a while to fix it.

Basically, ensure that you set the system memory of your VM to be larger than 512MB, otherwise you might see black screen after booting your VM from the Mint DVD installation.

Once the installation is finished, feel free to reduce the VM’s system memory to 512MB or smaller.

Progamming Arduino using USBasp on Ubuntu

Sat, 13 Sep 2014 20:13:36 +0000

My USBAsp dongle arrived from China. It’s connected to the ISCP pins on an Arduino Nano, and also plugged to a computer via USB connection.

According to lots of intructions on the Internet, to upload a sketch to an Arduino, we need to do the following steps:

Tools -> Programmer -> USBasp
File -> Upload Using Programmer

Unfortunatly, it did not work for me. Here is the error message produced by Arduino IDE:

Windows 7 Boot Error with MpFilter.sys corrupted

Thu, 11 Sep 2014 16:48:47 +0000

After doing patch-Tuesday update yesterday, my Windows 7 no longer booted. This is the second time it happened. Last time I fixed it, didn’t get to document and it took me a while to figure out how I did it.

This version of Windows is Windows 7 Professional 32-bit. After some digging, MpFilter.sys is Microsoft Malware Protection Minifilter, which is a part of Microsoft Security Essentials (MSE). MSE is installed on my Windows 7 machine.

Arduino improving nRF24L01+ reliability

Tue, 12 Aug 2014 23:08:29 +0000

In the past few weeks, I noticed that data transmitting from one of sensor nodes got dropped dramatically. This sensor node is an Arduino Micro using nRF24L01+ as the transmitter.

Well, it’s supposed to send data to the base station once every 30 seconds; however the transmitting recurrence time exceeded 2 minutes. By default the transmitting rate is at 1 Mb/s, so I dropped it to 250 Kb/s to see if had any better improvement. It didn’t help.

Python: How to convert a list to a string

Sat, 02 Aug 2014 10:47:55 +0000

There must already exist a gazillion articles about how to do this; but one more won’t hurt, right?

Suppose you have a list, called alist, as the following:

In [2]: alist
Out[2]: ['apple', 'banana', 'pear']

To create a string from “alist” with a comma separator, we can do this:

In [3]: ','.join(alist)
Out[3]: 'apple,banana,pear'

Basically, you can place a desired separator in the ',' or omit it totally.

Reference: http://www.decalage.info/en/python/print_list

Set Timezone in Fedora 20

Mon, 21 Jul 2014 23:09:50 +0000

While looking at the log file on my Raspberry Pi (running Fedora 20 Remix), I noticed that the date/time didn’t look right.

# date
Mon Jul 21 09:01:18 EDT 2014
# timedatectl 
      Local time: Mon 2014-07-21 08:56:16 EDT
  Universal time: Mon 2014-07-21 12:56:16 UTC
        Timezone: n/a (EDT, -0400)
     NTP enabled: yes
NTP synchronized: yes
 RTC in local TZ: no
      DST active: yes
 Last DST change: DST began at
                  Sun 2014-03-09 01:59:59 EST
                  Sun 2014-03-09 03:00:00 EDT
 Next DST change: DST ends (the clock jumps one hour backwards) at
                  Sun 2014-11-02 01:59:59 EDT
                  Sun 2014-11-02 01:00:00 EST

EDT is a North American Eastern Daylight Time, which is 4 hours behind UTC. You can read more about it here. In my case, I prefer the time zone set to AEST (Australian Eastern Standard Time), which is 10 hour ahead of UTC.

systemd - start, status, enable example

Thu, 17 Jul 2014 16:56:40 +0000

This is just a quick note to remind myself how to enable or disable services using Systemd. In this example, I’m using denyhosts service.

Check if a service is running.

# systemctl status denyhosts
denyhosts.service - SSH log watcher
   Loaded: loaded (/usr/lib/systemd/system/denyhosts.service; disabled)
   Active: inactive (dead)

Start a service and verify its running status:

# systemctl start denyhosts
# systemctl status denyhosts
denyhosts.service - SSH log watcher
   Loaded: loaded (/usr/lib/systemd/system/denyhosts.service; disabled)
   Active: active (running) since Thu 2014-07-17 01:44:29 EDT; 1min 25s ago
  Process: 15722 ExecStart=/usr/bin/denyhosts.py --daemon --config=/etc/denyhosts.conf (code=exited, status=0/SUCCESS)
  Process: 15719 ExecStartPre=/bin/rm -f /run/lock/subsys/denyhosts (code=exited, status=0/SUCCESS)
 Main PID: 19367 (denyhosts.py)
   CGroup: /system.slice/denyhosts.service
           └─19367 /usr/bin/python /usr/bin/denyhosts.py --daemon --config=/etc/denyhosts.conf

Jul 17 01:44:29 pidora.local systemd[1]: PID file /run/lock/subsys/denyhosts not readable (yet?) after start.
Jul 17 01:44:29 pidora.local systemd[1]: Started SSH log watcher.

Check if a denyhosts service is enabled or not:

Managing LVM

Fri, 04 Jul 2014 16:37:13 +0000

LVM stands for Logical Volume Manager. It is a tool for logical volume management allowing us to allocate disks, strip, mirror and resize logical volumes. With LVM, we can manage partitions dynamically.

Recently at work, we opted to use LVM to create logical partitions instead of physical partition on Linux desktop. This post is just a note to remind me of some common used commands. If you want to learn more about LVM, hit this link instead.

Eclipse ADT Fatal Error on Linux

Wed, 02 Jul 2014 14:23:56 +0000

The Eclipse IDE that comes bundle with Android Development Tools (ADT) crashes when run on my laptop running Fedora.

The error message which logged to console is:

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x0000003cc2270061, pid=9653, tid=140330452297472
#
# JRE version: Java(TM) SE Runtime Environment (7.0_55-b13) (build 1.7.0_55-b13)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (24.55-b03 mixed mode linux-amd64 compressed oops)
# Problematic frame:
# C  [libsoup-2.4.so.1+0x70061]  soup_session_feature_detach+0x11
#
# Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#

Fortunately, there’s a way to fix this problem by opening ‘eclipse.ini’ file, in my case:

Running Kompare from command line

Wed, 11 Jun 2014 14:05:11 +0000

Recently I started to use Kompare a lot to compare the differences between two files. The way I compare two files is to open both files from the menu (File -> Compare Files). This is annoying and how I wish there were a way to just run Kompare from the command line passing 2 files as options.

Well, it looks like my wish has been granted. I found the information here on how to do just that:

New P&E OpenSDA Firmware v115 for K20D50M

Tue, 03 Jun 2014 21:03:04 +0000

Having trouble uploading compiled code to K20D50M board? There’s a new firmware that (should) fix this.

A few weeks ago, I’ve updated the OpenSDA firmware on my Freescale FRDM-K20D50M to v114 only to find out that it no longer let me uploading any compiled files to the board.

At first I thought my board was faulty, but felt relieved to hear that Erich Styger, an mbed expert, confirming this v114 firwmare also affected his K20D50M. Erich contacted P&E, and they in turn confirmed the problem.

MongoDB warning: Failed to connect

Thu, 22 May 2014 16:44:32 +0000

After upgrading MongoDB from version 2.4 to 2.6, I am not able to connect to it from another machine. The firewall has been checked to ensure that port 27017 is opened for the machine that I want to connect from.

So what else could go wrong? Well, I was impatient and turned to you know what… Google search. According to this link: https://groups.google.com/forum/#!msg/mongodb-user/yhf05AW-hK8/YqES0cVIXlUJ, the problem is due to the database is bound to only local IP.

FreeBSD 10: Shared object 'libstdc++.so.6' not found

Fri, 25 Apr 2014 11:53:53 +0000

Today while I was updating py27-m2crypto package on FreeBSD 10 using portmaster, the following error message was displayed:

Shared object "libstdc++.so.6" not found, required by "swig"

Fortunately, someone else has found the problem and solution before me. According this blog post, FreeBSD 10 includes a new C++ stack and gcc, including libstdc++, is not installed by default.

Therefore, to fix the missing this libstdc++.so.6 issue, we need to install lang/gcc.

If you use portmaster, the command to install lang/gcc is:

moserial - a serial terminal for Linux

Tue, 22 Apr 2014 21:38:06 +0000

The real tag line for moserial is “a serial terminal for the GNOME desktop”. However, since it’s installed just fine on my KDE desktop, I titled this post as “moserial - a serial terminal for Linux”. (Well, it probably works on servers as well, not just desktop.)

So what is this moserial? It’s a terminal which allows you to connect to view or send data to a serial port. For example, a lot of mbed device or micro controllers, such as Arduino, can be configured to send/receive data via serial port. Before I found out about this program, I normally open up Arduinio IDE and connect to the Arduino via Serial Monitor function. Now, I never look back after using moserial.

Puppet agent hangs after loading facts

Tue, 22 Apr 2014 11:37:51 +0000

At my current work place, we use Puppet to manage desktop machines. Recently, I need to prepare an new image based on Ubuntu 14.04 LTS.

To prepare an image, in brief, first thing is to install a fresh Ubuntu on a machine, compile and package lots of applications, and make change to configuration such as look and feels, etc. As mentioned earlier, I use Puppet to manage machine, so I store all customed configuration on the Puppet server.

How to test cron

Tue, 18 Feb 2014 14:33:22 +0000

So you drop a script in /etc/cron.daily. How to check if that script does what it is expected to do without having to wait, in this case, a day?

Here is how:

# run-parts -v /etc/cron.daily

Reference:

http://stackoverflow.com/questions/4984725/how-to-test-cron-job

Can't find the 'libpq-fe.h header

Mon, 03 Feb 2014 12:59:10 +0000

I need to install pg 0.17.1 gem on a server running CentOS. This is the error message I saw:

# gem install pg -v '0.17.1'
Building native extensions.  This could take a while...
ERROR:  Error installing pg:
        ERROR: Failed to build gem native extension.

/usr/bin/ruby extconf.rb
checking for pg_config... no
No pg_config... trying anyway. If building fails, please try again with
 --with-pg-config=/path/to/pg_config
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.
...

First thing came to my mind was I must have forgotten to install the -dev package.

PostgreSQL: Peer authentication failed for user

Thu, 23 Jan 2014 10:53:12 +0000

Ever since Oracle took the ownership of MySQL, I’ve been leaning more and more toward PostgreSQL, or other NoSQL database like MongoDB.

Also, I’m not completely new to PostgreSQL, but the fact that I only have to touch it once in awhile, makes me feel PostgreSQL is so hard to use and missing the goold-oldie MySQL.

Anyway, this is the issue I had:

# su - postgres
-bash-4.1$ psql -l
                                   List of databases
    Name     |  Owner   | Encoding |   Collate   |    Ctype    |   Access privileges
-------------+----------+----------+-------------+-------------+-----------------------
 postgres    | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |
 postgres-db | postgres | UTF8     | en_US.UTF8  | en_US.UTF8  |
 puppetdb    | puppetdb | UTF8     | en_US.UTF8  | en_US.UTF8  |
 template0   | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +
             |          |          |             |             | postgres=CTc/postgres
 template1   | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +
             |          |          |             |             | postgres=CTc/postgres
(5 rows)

-bash-4.1$ psql -d puppetdb -U puppetdb --password
Password for user puppetdb:
psql: FATAL:  Peer authentication failed for user "puppetdb"

To fix it, we need to modify pg_hba.conf, which is located in the /var/lib/pgsql/9.3/data/ directory on my system.

How to suspend/hibernate from command line

Mon, 06 Jan 2014 09:22:35 +0000

First find out what states your system is supported:

$ cat /sys/power/state
mem disk

To suspend to ram:

# echo -n mem > /sys/power/state

To hibernate:

# echo -n disk > /sys/power/state

Ref: http://askubuntu.com/questions/1792/how-can-i-suspend-hibernate-from-command-line

Installing Plasma on Fedora 20

Thu, 02 Jan 2014 15:07:10 +0000

From the command line:

# yum install -y kde-runtime.x86_64 kdm @kde-desktop

Optionally, if you want to run KDM instead of GDM:

# systemctl disable gdm
# systemctl stop gdm
# systemctl start kdm

Note: This guide should work on Fedora 19 as well; but I haven’t tested it.

Source: http://marcofalchi.blogspot.com.au/2013/10/fedora-1920-install-kde-kdm-swith-from.html

How to extract .xz file

Sun, 29 Dec 2013 20:41:10 +0000

Today is the first time I ever saw a compressed file in *.xz format. According to this page TIP: extract .xz format, we can decompress it by running the following command:

$ unxz sample.xz

Just make sure you have “xz-utils” package, on Debian system, or something equivalent on other distros installed.

Setting proxy for CPAN

Fri, 15 Nov 2013 12:45:05 +0000

To enable CPAN behind proxy:

# perl -MCPAN -e shell
Terminal does not support AddHistory.

cpan shell -- CPAN exploration and modules installation (v1.9402)
Enter 'h' for help.

cpan[1]> o conf init /proxy/

If you're accessing the net via proxies, you can specify them in the
CPAN configuration or via environment variables. The variable in
the $CPAN::Config takes precedence.

 <ftp_proxy>
Your ftp_proxy? []

 <http_proxy>
Your http_proxy? [webproxy.yourdomain.com:8080]

 <no_proxy>
Your no_proxy? []

If your proxy is an authenticating proxy, you can store your username
permanently. If you do not want that, just press RETURN. You will then
be asked for your username in every future session.

Your proxy user id? []

Please remember to call 'o conf commit' to make the config permanent!

cpan[2]> o conf commit
commit: wrote '/usr/share/perl5/CPAN/Config.pm'

Ref:

Install Google Chrome on Fedora 19

Fri, 15 Nov 2013 10:52:20 +0000

Add the following to /etc/yum.repos.d/google-chrome.repo:

google-chrome]
name=google-chrome - 64-bit
baseurl=http://dl.google.com/linux/chrome/rpm/stable/x86_64
enabled=1
gpgcheck=1
gpgkey=https://dl-ssl.google.com/linux/linux_signing_key.pub

Pick a version, stable, beta or unstable and install with the following command:

# yum install google-chrome-stable

Ref: http://www.if-not-true-then-false.com/2010/install-google-chrome-with-yum-on-fedora-red-hat-rhel/

Permanently Disable Search Indexing In Windows 8

Mon, 04 Nov 2013 10:17:10 +0000

This post is mainly to remind me how to disable the search indexing.

On the start screen type: services.msc. Once the service dialog windows opened, look for “Windows Search”. Right click on it, and select Properties. In the Startup type drop-down list, select Disabled.

Full credit goes to this link: http://www.addictivetips.com/windows-tips/how-to-permanently-disable-search-indexing-in-windows-8/.

Upgrade existing Perl 5.12 to Perl 5.18 on FreeBSD 9

Wed, 30 Oct 2013 12:20:19 +0000

Recently I’ve been trying to update the perl package on my FreeBSD box to the latest version 5.18 without any success. Here’s a snippet of the error message:

Creating various symlinks in /usr/bin...
    Symlinking /usr/local/bin/perl5.18.1 to /usr/bin/perl
    Symlinking /usr/local/bin/perl5.18.1 to /usr/bin/perl5
Done.
Installing perl5.18-5.18.1_2...pkg-static: perl5.18-5.18.1_2 conflicts with perl-5.12.5 (installs files into the same place).  Problematic file: /usr/local/bin/a2p
*** [fake-pkg] Error code 70
Stop in /usr/ports/lang/perl5.18.
*** [install] Error code 1

Stop in /usr/ports/lang/perl5.18.

===>>> Installation of perl5.18-5.18.1_2 (lang/perl5.18) failed
===>>> Aborting update

===>>> Killing background jobs
Terminated

===>>> You can restart from the point of failure with this command line:
portmaster lang/perl5.18

===>>> Exiting

So I turned to Google to see if other people experienced the same thing as me. According to an answer to a similar question about upgrading perl on serverfault.com, one should read

ZFS on CentOS

Tue, 08 Oct 2013 07:55:46 +0000

First we need to add the ZFS on Linux repository to our system by installing a zfs-release package as shown below:

$ sudo yum localinstall --nogpgcheck http://archive.zfsonlinux.org/epel/zfs-release-1-3.el6.noarch.rpm
$ sudo yum install zfs

Once, zfs has been installed, we can create a storage pool. There’re many RAID configuration to choose from, and I’m not going to get into it. However, if you want to learn more, you can read this ZFS Administration article which explains in great detail about ZFS RAID(Z).

Portsnap snapshot corrupt

Mon, 07 Oct 2013 08:15:10 +0000

ថ្ងៃនេះខ្ញុំមានបញ្ហាជាមួយ portsnap លើ FreeBSD ស៊ើវើ។ ពេលខ្ញុំរត់ខំម៉ាន portsnap fetch upate មានពត៌មានដូចនេះ

/usr/ports/files/.gz not found — snapshot corrupt.

តាមប្លក់នេះ របៀបជួសជុលវា មិនពិបាកទេ។

rm -rf /var/db/portsnap/*
portsnap fetch
portsnap extract

Source: http://neonpulse.net/2008/11/20/portsnap-corrupt-snapshot/

E: Internal Error, No file name for libapt-pkg4.12

Thu, 03 Oct 2013 00:24:34 +0000

When I tried to update an Ubuntu (12.04) machine with the usual apt-get command, this error message came up:

Do you want to continue [Y/n]? Y
E: Internal Error, No file name for libapt-pkg4.12

Reading this post (http://ubuntuforums.org/showthread.php?t=2045321), one way to fix it is to download liapt-pkg4.12 and re-install it:

# apt-get download libapt-pkg4.12/precise-security
# dpkg -i libapt-pkg4.12_0.8.16~exp12ubuntu10.10_amd64.deb

This seems did the trick.

បញ្ចូល Upstream Version នៃ Node.js ក្នុង Ubuntu 12.04

Tue, 01 Oct 2013 05:11:15 +0000

$ sudo apt-get install python-software-properties
$ sudo apt-add-repository ppa:chris-lea/node.js
$ sudo apt-get update
$ sudo apt-get install nodejs

ឆែកមើល:

$ node -v
v0.10.20

Turn color on for git status

Thu, 26 Sep 2013 03:49:33 +0000

The following command will update the Git’s global configuration to set the color.ui to true.

$ git config --global color.ui true

Ref: https://ask.fedoraproject.org/question/10434

Changing ZFS pool to use disk ID instead of disk assignment

Fri, 20 Sep 2013 06:49:51 +0000

This what I have:

# zpool status
  pool: tank
 state: ONLINE
  scan: none requested
config:

        NAME        STATE     READ WRITE CKSUM
        tank        ONLINE       0     0     0
          raidz1-0  ONLINE       0     0     0
            sdb     ONLINE       0     0     0
            sdc     ONLINE       0     0     0
            sdd     ONLINE       0     0     0

To convert the pool to use disk’s ID instead of device files such as /dev/sda, we need to export the storage pool.

Install Python 3 on CentOS 6

Wed, 04 Sep 2013 06:00:26 +0000

The latest release of Python 3 is 3.3.2, and there’s no package available on CentOS repo via yum. The following steps explains how to manually get Python 3 onto a CentOS system:

Install development tools

# yum groupinstall "Development Tools"

# yum install zlib-devel bzip2-devel openssl-devel \
ncurses-devel sqlite-devel readline-devel tk-devel

Download and install Python

$ wget http://python.org/ftp/python/3.3.2/Python-3.3.2.tar.bz2
$ tar xjf Python-3.3.2.tar.bz2
$ cd Python-3.3.2
$ ./configure --prefix=/opt/python3
$ make
$ make install</pre>

Test

How to Fix a PuppetDB SSL Error

Thu, 22 Aug 2013 05:34:05 +0000

If you don’t know what PuppetDB is, this post probably will not be useful to you. But if you want to learn about it, you can visit the official documentation: http://docs.puppetlabs.com/puppetdb/latest/index.html.

For PuppetDB to work, it needs SSL certificates generated by a Puppet master. In my case, I needed to reconfigure an existing PuppetDB instance to use a new Puppet master that was running on the same server. Here’s how I did it:

FreeBSD configure: error: XML::Parser perl module is required for intltool

Wed, 24 Jul 2013 06:13:03 +0000

If you get this error message on a FreeBSD host, you may need to reinstall p5-XML-Parser.

# portmaster textproc/p5-XML-Parser

Upgrading from Fedora 18 to 19

Tue, 02 Jul 2013 16:06:59 +0000

I know Fedora 19 is officially released tomorrow; but if you can’t wait to upgrade your machine to the latest release like me, here is the command to do it:

$ sudo fedup --network 19

One thing I noticed after the upgrade is that, the bottom status bar can’t be found when you hit the system key. The good news is it’s still there; you just need to hit system key + m to have it showed up.

Install crontab on CentOS 6

Mon, 27 May 2013 14:33:26 +0000

When you install CentOS 6 using minimal CD, a lot of packages aren’t installed by default; cron included. To install it,

# yum install cronie

After the installation, you can verify that crond is running:

# chkconfig --list crond
crond 0:off 1:off 2:on 3:on 4:on 5:on 6:off

Fix puppet-dashboard pending tasks

Tue, 30 Apr 2013 05:43:47 +0000

ផាប់ភិតដាសបត ឈប់ដើរ ហើយ pending tasks មានប្រហែលជាង ២០០០។

# ps -ef | grep job
www-data  4799     1  0 14:07 ?        00:00:00 delayed_job.0_monitor
www-data  4804     1  0 14:07 ?        00:00:00 delayed_job.1_monitor
root      8300 31461  0 15:22 pts/0    00:00:00 grep job

មិនដឹងថាជាមានវិធីល្អ សំរាប់ជួសជុលបញ្ហានេះទេ ប៉ុន្តែខ្ញុំអាច ប្រើវិធីដូចនេះ

# cd /usr/share/puppet-dashboard/
# rake RAILS_ENV=production jobs:work

អោយវារត់ យ៉ាងយូរ បន្ទាប់មក puppet-dashboard-worker ក៏ចាប់ផ្តើមដើរវិញ

# ps -ef | grep job
www-data  4799     1  0 14:07 ?        00:00:00 delayed_job.0_monitor
www-data  4804     1  0 14:07 ?        00:00:00 delayed_job.1_monitor
www-data  5089     1 24 14:15 ?        00:20:43 dashboard/delayed_job.0
www-data  5094     1 24 14:15 ?        00:20:45 dashboard/delayed_job.1
root      8570 31461  0 15:41 pts/0    00:00:00 grep job

vmware: CD/DVD ROM drive is stuck in connecting mode

Mon, 11 Feb 2013 03:39:04 +0000

As the title says, if the CD/DVD device of your VM is stuck in connecting mode, one thing to try is to shutdown the vSphere client, and restarted it.

I found this solution from http://communities.vmware.com/message/1784438, and it worked for me.

PHP Fatal error: Call to undefined function utf8_decode()

Tue, 25 Dec 2012 03:57:20 +0000

This occurs on a FreeBSD server. According to this post[1], I need to install php5-xmlphp5-xml.

# whereis php5-xmlphp5-xml
php5-xml: /usr/ports/textproc/php5-xml
# portmaster textproc/php5-xml
...
# service apache22 restart

[1] http://hi.baidu.com/ericyangbj/item/8289a32771e4171d09750856

FreeBSD: Fatal error: Call to undefined function session_name()

Tue, 25 Dec 2012 00:08:49 +0000

I just setup Apache and PHP on FreeBSD 9, configured a vhost, then when I tried to access it, I got the following error:

Fatal error: Call to undefined function session_name() in /srv/www/sugaku.domain.com/inc/init.php on line 144

so apparently, the “session” support is missiong from php5 installation. To fix it, I need to install php5-session port.

Let’s do it.

# whereis php5-session php5-session: /usr/ports/www/php5-session portmaster www/php5-session

If the installation is successful, then we can restart apache.

CentOS: lsb_release: command not found

Sun, 21 Oct 2012 22:53:07 +0000

First let me declare that I’m new to CentOS. The folowing is a note to self which demonstrates how we search for a package that provides some commands and intall it using yum on CentOS.

When I ran ‘lsb_release -a’, the following message is returned:

-bash: lbs_release: command not found

To fix it, we need to install the package which provides lsb_release command.

# yum provides */lsb_release
...
redhat-lsb-4.0-3.el6.centos.i686 : LSB base libraries support for CentOS
Repo        : base
Matched from:
Filename    : /usr/bin/lsb_release

redhat-lsb-4.0-3.el6.centos.x86_64 : LSB base libraries support for CentOS
Repo        : base
Matched from:
Filename    : /usr/bin/lsb_release

dkms-2.2.0.3-2.el6.noarch : Dynamic Kernel Module Support Framework
Repo        : epel
Matched from:
Filename    : /usr/lib/dkms/lsb_release

So, let’s install redhat-lsb package:

Turn on puppet syntax highlight in vim

Fri, 21 Sep 2012 02:01:47 +0000

On Debian/Ubuntu:

$ sudo apt-get install vim-puppet
$ ln -s /usr/share/vim/addons/syntax/puppet.vim ~/.vim/plugin/

Fix missing icons and ugly theme in Evolution on Kubuntu 11.10

Tue, 18 Sep 2012 06:43:05 +0000

This how Evolution looks like on Kubuntu 11.10 (Oneiric).

To fix this, make sure this package is installed: “humanity-icon-theme”, then create $HOME/.config/gtk-3.0/settings.ini.

[Settings]
gtk-fallback-icon-theme = Humanity

Restart Evolution, and it should be fixed.

Credit: [solution] Evolution in Kubuntu 11.10

Unknown Authn provider: ldap

Wed, 12 Sep 2012 00:11:38 +0000

Unknown Authn provider: ldap

a2enmod authnz_ldap apache2ctl restart

Fix: Xfce 4.10 panel no longer expands

Fri, 24 Aug 2012 01:35:35 +0000

After upgrading to Xfce 4.10 from 4.8, I noticed that the clock/notification area no longer pushed to the right edge of the panel.

This is due to a change in the Window Buttons panel plugin which no longer expands to fill the available space[1].

To emulate the old behavior, add a transparent separator between the window buttons and the clock/notification area, setting its expand property.

Voilla!

[1] https://wiki.archlinux.org/index.php/Xfce

FreeNX: Disable Persistent Session

Wed, 22 Aug 2012 00:42:18 +0000

It’s a bit unintuitive to set non-persistent session on FreeNX server. After a few attempts, here is the working settings:

Edit /usr/NX/etc/node.cfg:

ENABLE_PERSISTENT_SESSION="" DISABLE_PERSISTENT_SESSION="all"

KDE Desktop Shell Scripting Console

Thu, 16 Aug 2012 01:47:03 +0000

I keep forgetting how to run Desktop Shell Scripting Console. So here it is, something just to remind myself:

Alt + F2
Type desktop console and hit the enter key

Wanna learn more what this tool’s for? Head to KDE System Administration/PlasmaDesktopScripting.

Vim backspace delete problem

Tue, 07 Aug 2012 12:21:17 +0000

In insert mode, backpace doesn’t delete characters as intended. To fix this issue, add this configuration to the .vimrc as the following:

set backspace=indent,eol,start

Reference:

http://vim.wikia.com/wiki/Backspace_and_delete_problems

FreeBSD: How to check version of installed packages

Wed, 01 Aug 2012 22:52:43 +0000

# pkg_version -v

Running pkg_version -v could take a while. If we only want a quick look:

# pkg_info -xI

If we want to see if some packages are out of date:

# pkg_version -v -X -s

And to check all out of date packages:

# pkg_version -vL "="

Installing FreeBSD 9 source

Sun, 29 Jul 2012 12:01:21 +0000

Well, I need FreebSD 9 source to compile fusefs-kmod, which is required by gvfs, which’s in turn required by xfce.

A lot of people recommend to use sysinstall to add the so called userland sources.

sysinstall -> Configure -> Distribution -> src

However, it didn’t work!!

Thanks to wblock@[1] who pointed out that “sysinstall is mostly dead” and suggested a few ways to get the sources to your system. One of them is:

Change cursor theme in Xfce on Freebsd

Thu, 26 Jul 2012 11:19:29 +0000

Install the preferred cursor theme. I personally like dmz-cursor-theme.

# pkg_add -r cursor-dmz-theme

Then, Applications Menu -> Settings -> Mouse. Click on Theme tab, select the preferred theme and click Close.
Log out of the current Xfce session, then log back in.

KDE4 System-wide Force Font DPI Setting

Sun, 22 Jul 2012 01:17:22 +0000

Recently, while setting up a Kubuntu Linux terminal server using freenx, I’ve got an issue with the font display being too small. A quick check in Font settings (Applications -> Settings -> System Settings -> Fonts) showed that the “Force fonts DPI” was set to Disabled.

To correct this per user, it’s as easy as to select the 96 DPI from the drop down menu, logout and log back in. However, if we want to apply this setting to all users, there’s a bit of more work.

បញ្ចូល C/C++ plugin (or CDT) ក្នុង Eclipse

Fri, 20 Jul 2012 00:39:36 +0000

សំណាងល្អ អ៊ូប៊ុនធូ មានកញ្ចប់មួយឈ្មោះ eclipse-cdt ។

យើងអាចបញ្ចូលវាដោយ ខំម៉ានដូចនេះ

$ sudo apt-get install eclipse-cdt

ពេលបើក Eclipse លើកក្រោយ ហើយបង្កើត project ថ្មី យើងនឹងឃើញស្រដៀងនេះ

Fix: (K)ubuntu doesn’t play Audio CD

Wed, 11 Jul 2012 01:49:55 +0000

On Kubuntu 11.10, we have KsCD program installed to play audio CD. The problem I’m having is that some machines could play audio cd and some couldn’t. All machines run Kubuntu 11.10.

To fix this issue, check that /dev/cdrom is a sym link to /dev/sr0 (credit [1]).

In my case, machines which couldn’t play audio CD don’t have ‘/dev/cdrom’:

# ls -l /dev/cd*
ls: cannot access /dev/cd*: No such file or directory

Let’s create one:

svc: failed to register lockdv1 RPC service (errno 97).

Fri, 11 Nov 2011 12:49:56 +0000

It started with… when I tried to start nfs-kernel-server, it just failed.

# /etc/init.d/nfs-kernel-server start
Exporting directories for NFS kernel daemon....
Starting NFS kernel daemon: nfsd svcgssd failed!

syslogs:

Nov 11 23:32:04 nasbox kernel: [ 8106.165582] nfsd: last server has exited, flushing export cache
Nov 11 23:32:05 nasbox kernel: [ 8107.240419] svc: failed to register lockdv1 RPC service (errno 97).
Nov 11 23:32:05 nasbox kernel: [ 8107.245528] NFSD: Using /var/lib/nfs/v4recovery as the NFSv4 state recovery directory
Nov 11 23:32:05 nasbox kernel: [ 8107.245566] NFSD: starting 90-second grace period
Nov 11 23:32:05 nasbox rpc.svcgssd[26744]: ERROR: GSS-API: error in gss_acquire_cred(): Unspecified GSS failure. Minor code may provide more information - Key table entry not found
Nov 11 23:32:05 nasbox rpc.svcgssd[26744]: unable to obtain root (machine) credentials
Nov 11 23:32:05 nasbox rpc.svcgssd[26744]: do you have a keytab entry for nfs/@ in /etc/krb5.keytab?

If you have DNS server running, make sure you remove the following lines from /etc/hosts:

Ubuntu 11.10: 32-bit applications do not run 64-bit

Thu, 27 Oct 2011 11:47:05 +0000

After upgrading from natty (11.04) to oneiric (11.10), some 32-bit applications don’t run anymore. I have ‘ia32-libs’ and ‘libc6-i386’ packages installed. For example, when I run Android adb,

$ ./adb
bash: ./adb: No such file or directory
$ file adb
adb: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.8, stripped

After googling around, the fix is quite simple: re-install ‘libc6-i386’.

$ sudo apt-get install --reinstall libc6-i386
$ ./adb
Android Debug Bridge version 1.0.29
 -d                            - directs command to the only connected USB device
                                 returns an error if more than one USB device is present.
 -e                            - directs command to the only running emulator.
...

Reference:

How to decompress .tar.Z

Thu, 06 Oct 2011 05:17:52 +0000

One way to extract a .tar.Z file:

$ zcat file.tar.Z | tar xvf -

Beautify gitk font on Debian/Ubuntu

Sun, 04 Sep 2011 11:35:11 +0000

Install tk8.5, if not yet installed:

# apt-get install tk8.5
# update-alternatives --config wish

  Selection    Alternative
-----------------------------------------------
          1    /usr/bin/wish8.4
*+        2    /usr/bin/wish-default
          3    /usr/bin/wish8.5</pre>

There are 3 alternatives which provide wish.

Type in the number that corresponds to tk8.5 (in my case was 3) then hit enter.

Change fonts in ~/.gitk to DejaVu Sans Mono.

set mainfont {{DejaVu Sans Mono} 9}
set textfont {{DejaVu Sans Mono} 9}
set uifont {{DejaVu Sans Mono} 9 bold}

How to replace default fonts in MIUI rom

Sun, 24 Jul 2011 02:35:46 +0000

MIUI (1.7.22) uses Arial as the default font. If you hate it as I do, here is how to change it.

I assume you have adb working. We are going to replace only 2 fonts - Arial.ttf and Arial-Bold.ttf.

First, let’s back up the old fonts just in case thing didn’t go well as we want to. (I learned this the hard way, and keen to avoid it at all cost)

PHP extension "mcrypt" must be loaded.

Sun, 22 May 2011 05:12:54 +0000

On Ubuntu or Debian:

$ sudo apt-cache search php|egrep ^php5-
$ sudo apt-get install php5-mcrypt

Ref: Install php extensions on ubuntu

Kill all processes of a user

Mon, 09 May 2011 23:58:54 +0000

The following command will kill all processes belong to a single user on Linux.

pkill -u username

Credit: Linux – Kill all processes for a user

[FIXED] bind9 is running bind9 status reports failed!

Sun, 19 Dec 2010 00:41:58 +0000

bind9 runs in a chroot environment on lenny. The service can be started as usual:

# /etc/init.d/bind9 start
Starting domain name service...: bind9.

Let’s check bind9 status:

/etc/init.d/bind9 status

bind9 is not running failed! `

Well, the first thing I did was to check the log file, in which I found no error related to named. So I tried another way to check the status:

# rndc status
version: 9.6-ESV-R3
CPUs found: 1
worker threads: 1
number of zones: 17
debug level: 0
xfers running: 0
xfers deferred: 0
soa queries in progress: 0
query logging is OFF
recursive clients: 0/0/1000
tcp clients: 0/100
server is up and running

I was convinced that the DNS service was running. So what went wrong? It must be something in the /etc/init.d/bind9 script that incorrectly reports bind9 status. Opened up this file, I found:

What the heck: three.net.au redirecting to www.policywording.com.au

Thu, 09 Dec 2010 13:31:21 +0000

3 is my mobile carrier. It offers an online service which allows its customers to check the current usage from their phones by accessing this URL: three.net.au/my3/gethome.do.

Usually it works quite well, but not today (and probably some more days to come), it gave me a HTTP ERROR 404. I thought I should just visit http://three.net.au and find out w-t-h is wrong. Unexpectedly it took me to another site — “callenden group policy wording”. It’s very weird so with some spare time, I decided to do a little investigation.

Banshee freezes when opened

Sun, 28 Nov 2010 11:35:07 +0000

This is a self-note.

$ banshee --disable-dbus

[Fixed] K3b doesn’t burn mp3 to CD

Sat, 06 Nov 2010 13:41:03 +0000

On Ubuntu 10.10, if you get an error message as the following when trying to create audio CD from mp3:

“Unable to handle the following files due to an unsupported format:

You may manually convert these audio files to wave using another application supporting the audio format and then add the wave files to the K3b project.”

Check if you have libk3b6-extracodecs installed, if not just;

$ sudo apt-get install libk3b6-extracodecs

Can’t locate Net/LDAP.pm

Mon, 25 Oct 2010 03:44:01 +0000

On Debian:

# apt-get install libnet-ldap-perl

Banshee crashes: The database disk image is malformed

Tue, 28 Sep 2010 11:46:02 +0000

Banshee just crashed on me with the following error message:

[Info  20:44:59.949] Running Banshee 1.6.1: [Ubuntu 10.04 LTS (linux-gnu, x86_64) @ 2010-06-18 18:47:49 UTC]
[Info  20:45:01.043] All services are started 0.949921
Exception has been thrown by the target of an invocation.
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> Mono.Data.Sqlite.SqliteException: <strong>The database disk image is malformed</strong>
database disk image is malformed
at Mono.Data.Sqlite.Sqlite3.Reset (Mono.Data.Sqlite.SqliteStatement stmt) [0x00000]
at Mono.Data.Sqlite.Sqlite3.Step (Mono.Data.Sqlite.SqliteStatement stmt) [0x00000]
at Mono.Data.Sqlite.SqliteCommand.ExecuteNonQuery () [0x00000]
at (wrapper remoting-invoke-with-check) Mono.Data.Sqlite.SqliteCommand:ExecuteNonQuery ()
at Hyena.Data.Sqlite.HyenaSqliteCommand.Execute (Hyena.Data.Sqlite.HyenaSqliteConnection hconnection, Mono.Data.Sqlite.SqliteConnection connection) [0x00000]
--- End of inner exception stack trace ---

I think this is how it happened. My computer hanged while Banshee was running, and I had to force reboot it. Hence, the Banshee database file was corrupted. Thanks to boombox1387 from Ubuntu forum, this problem can be fixed as the following:

Playing .ass subtitles with mplayer

Sun, 29 Aug 2010 11:57:35 +0000

$ mplayer -ass -sub subtitle.ass file.avi

Amarok 2.3.0 and PulseAudio Problem

Mon, 17 May 2010 09:13:32 +0000

Ever since I upgraded my Ubuntu desktop from 9.04 to 10.4, I have been having problems with Amarok dropping sound randomly. For example, if Amarok is playing the music and another program requires to use sound, Amarok will become silence.

One solution to restore sound in Amarok is to kill pulseaudio and restart Amarok. It works, but very annoying.

Fortunately, installing libxine1-gnome and configure Amarok to use Esound (ESD) instead of PulseAudio fixed the problem.

Change default editor in Debian

Mon, 19 Apr 2010 02:29:25 +0000

# update-alternatives --config editor`

There are 7 alternatives which provide \`editor`.

Selection Alternative
  
1 /bin/ed
  
+ 2 /bin/nano
  
3 /usr/bin/vim.tiny
  
* 4 /usr/bin/vim.basic
  
5 /usr/bin/nedit
  
6 /usr/bin/emacs21
  
7 /usr/bin/xemacs21

Press enter to keep the default[*], or type selection number: 6

Enable sudo insults

Thu, 15 Apr 2010 14:42:50 +0000

$ sudo visudo

Look for line begins with Defaults, and append insults to the end.

Defaults        env_reset,insults

Save it, and clear the sudo session (sudo -K), and try sudo with a wrong password. 🙂

Source: Enable sudo insults for some laughs

Enable Japanese input on Debian/Ubuntu

Sun, 14 Mar 2010 07:59:34 +0000

Normally, I would install Scim and Anthy for Japanese input method on Debian. Recently, I found an easier way to achieve the same thing, which is to use IBus instead of Scim.

Install ibus: sudo apt-get install ibus ibus-anthy ibus-gtk
From the menu, System -> Preferences -> IBus Preference. IBus Preference should detects that you have run IBus daemon yet, click “Yes” to run it.
You’ll be asked to edit your ~/.bashrc and add the following 3 lines:

export GTK_IM_MODULE=ibus
export XMODIFIERS=@im=ibus
export QT_IM_MODULE=ibus</pre>

Click on “Input Method” tab, if you don’t see “Japanese – Anthy” listed under the Input Method list, select “Japanese -> Anthy” from the “Select an input method” drop down list, then click Add.
You might want to restart X (logout and log back in)
Open a text editor, and hit Ctrl + Space to toggle the Japanese input method

Reference: Japanese Input with Karmic?

How to tell which Linux distro you are running

Wed, 03 Feb 2010 23:13:26 +0000

Update

Thanks to Jayen, there is a better way:

$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 9.10
Release:	9.10
Codename:	karmic

$ cat /etc/issue
Debian GNU/Linux squeeze/sid n l

$ cat /proc/version
Linux version 2.6.32-trunk-686 (Debian 2.6.32-5) (ben@decadent.org.uk) (gcc version 4.3.4 (Debian 4.3.4-6) ) #1 SMP Sun Jan 10 06:32:16 UTC 2010

Source: Which Linux Distro are you using??

Enable mp3 playback with Amarok on Ubuntu 9.10

Fri, 22 Jan 2010 10:07:13 +0000

I just installed Ubuntu 9.10 on my desktop. When I tried to play some mp3 files with Amarok 2.2.0, it didn’t make any sound though it played ogg without a problem.

Thanks to this post, mp3 play back can be enabled by installing libxine1-ffmpeg.

$ sudo apt-get install libxine1-ffmpeg

Credit: How to Play mp3 files with amarok in Ubuntu Linux 9.04

Stopping hard drive clicking noise on MSI U100

Sat, 28 Nov 2009 04:14:27 +0000

Finally, the OS X has been removed from MSI Wind U100, and completely replaced by Debian (testing).

Whenever the computer is idle, the hdd makes this weird clicking noise. To stop it, we can use hdparm to turn it off.

kenno@tora:~$ sudo hdparm -B 254 /dev/sda</p>

/dev/sda:
 setting Advanced Power Management level to 0xfe (254)
 APM_level      = 254

Source: MSI Wind – Gentoo Linux Wiki

Profile backup - Mozilla FireFox and Thunderbird

Thu, 13 Aug 2009 07:04:22 +0000

At work, a colleague is struggling to get his PC up and running for a few days now. To add an insult to injury, he also lost some of his Microsoft Outlook back up emails.

Seeing what happened to him, it’s a good reminder that I shall back up my files and emails too.

I use Mozilla Thunderbird (2.0.0.22), and I found a very nice tool to back up the emails (a.k.a profile). It’s called MozBackup.

SQL: Update with values from another table

Thu, 13 Aug 2009 05:37:17 +0000

UPDATE Log SET Username = u.Username, Name = u.Name FROM Users u Where u.Id = userid

Source: codesnippets.joyent.com

MS SQL: Reset identity seed

Thu, 13 Aug 2009 02:26:23 +0000

Occasionally, I need to reset the value of the identity column in MS SQL database. I keep forgetting how to do this, and have to search all the time.

So here is a note to myself:

DBCC CHECKIDENT (TableName, RESEED, 0)

Restore Grub Boot Loader

Sat, 08 Aug 2009 14:56:24 +0000

Warning: this guide is only a personal note to remind myself when I have to restore Grub again.

In my previous post, I had just installed Windows 7 as a dual boot with Debian on my Toshiba laptop. The following describe the steps taken to restore the Grub boot loader so that Debian can be started again.

I booted the laptop with Ubuntu Live CD, then open a Terminal. To get the partition tables, as a root execute the fdisk command:

Windows 7 64 bit on Toshiba Satellite A200

Sat, 08 Aug 2009 07:42:38 +0000

I just finished installing Windows 7 64-bit Ultimate edtion on my 1+ year old Toshiba laptop. The model is Satellite A200-*****.

The installation went smoothly, well almost. On the first boot, the graphic card driver, the finger print reader were automatically updated with Windows update. The only two devices which weren’t detected are: unknown device “ACPITOS6205” (bluetooth) and the Texas Instrument 5-in-1 card reader. The 64-bit driver for the bluetooth can be downloaded from: http://aps2.toshiba-tro.de/bluetooth/ thanks to this post at Toshiba Laptop forum.

Linq Read Inserted Id of a Record

Tue, 04 Aug 2009 05:20:54 +0000

Suppose we have the following code sinppets:

 private BlogDataContext db = new BlogDataContext (); ...

article.Created = DateTime.UtcNow;

article.Modified = DateTime.UtcNow;

db.Articles.InsertOnSubmit(article);

db.SubmitChanges( );

The ID of the article is automatically generated. How do we get the Id of the newly inserted record?

It turns out that the article is updated with the value of Id after the method SubmitChanges( ) is invoked. So, we can just get the Id this way:

Convert wav to m4a with GNU/Linux

Mon, 27 Jul 2009 12:16:52 +0000

There are probably a gazillion ways to do this. I use FAAC, Freeware Advanced Audio Coder, to do this job.

It works very well:

 faac originalfile.wav -o outputfile.m4a 

FIXED: extconf.rb:8:in 'require': no such file to load - mkmf (LoadError)

Sat, 25 Jul 2009 11:20:28 +0000

While reading Linux Journal Issue 181 today, I stumbled upon a section explaining about running Ruby on Rails on Apache using an Apache module called Phusion Passenger, also known as mod_rails.

To install Passenger, I followed the instruction provided in the magazine:

sudo gem install passenger

Unxpectedly, I got the following error:

Building native extensions.  This could take a while...
ERROR:  Error installing passenger:
ERROR: Failed to build gem native extension.

/usr/bin/ruby1.8 extconf.rb
extconf.rb:8:in `require': no such file to load -- mkmf (LoadError)
from extconf.rb:8

Gem files will remain installed in /usr/lib/ruby/gems/1.8/gems/fastthread-1.0.7 for inspection.
Results logged to /usr/lib/ruby/gems/1.8/gems/fastthread-1.0.7/ext/fastthread/gem_make.out

What’s happening? What did I do wrong?

Copy hard disks or partitions with dd

Tue, 14 Jul 2009 04:46:34 +0000

Warning: The following is for personal note only, and is not meant to be a tutorial or guide.

On Debian server at work, we have /home mounted to /dev/hda6 partition, and I want to move that to a new hard disk /dev/hdb.

First, I need to create the new partition on /dev/hdb using fdisk with a desired size. Then, use dd to copy the content from /dev/hda6 to /dev/hdb1.

# dd if=/dev/hda6 of=/dev/hdb1 bs=1024

The above command instructs dd to read the content from /dev/hda6 and writes it to /dev/hdb1. bs=1024 sets the block size to 1024 bytes.

Pidgin – Old Version of libpurple and "Unknown Protocol"

Fri, 10 Jul 2009 11:37:10 +0000

I fixed the Pidgin “Unknown Protocol” problem just five minutes after my previous post. I’m going to describe how I found the problem and how I fixed it. If you’re interested, keep reading.

In the previous post, I mentioned that I would completely remove the Pidgin package, including its configuration files:

# apt-get --purge remove pidgin

I did that and then re-installed Pidgin, but unfortunately, it didn’t fix anything.

Then I checked the About dialog (Help > About) and noticed it listed libpurple 2.5.4 under Pidgin 2.5.6. This had to be the source of the problem! I remembered that libpurple had been upgraded to 2.5.6, and Aptitude said so. So what could possibly be wrong?

Pidgin – Protocol Unknown (FIXED)

Fri, 10 Jul 2009 10:37:40 +0000

Update: The problem has been fixed. Please see this post.

A few weeks ago, Pidgin could not connect to the Yahoo! Messenger server because Yahoo! was changing its protocols. At the time, Pidgin was at version 2.5.5. Then that Yahoo! connection problem was fixed in version 2.5.7 and newer of Pidgin.

Anyway, Pidgin is acting up again. This time I’m not sure what is going on, and it didn’t seem other people are experiencing the same problem – Protocol Unknown for all types of accounts.

PHP: number of days between two dates

Sat, 04 Jul 2009 09:17:05 +0000

It’s Saturday, what am I doing in front of the computer? I should be out and enjoy life. ^o^

A colleague asked to customize a theme for his blog using WordPress. Because I didn’t have any good plan this Saturday, learning PHP sound like a logical and useful choice. Well, I bribed myself with a bottle of Tui.

Then, I found an interesting PHP related post by Chorn Sokun titled PHP date diff. The author was trying to calculate the number days between two give dates. At the end of the post, he asked “What would you do instead?”

Import photos from iPhone without iPhoto

Fri, 03 Jul 2009 00:18:14 +0000

So how do you transfer your photos from the iPhone 3G to your laptop running OS X if you don’t have iPhoto app? — Easy, just use the buit in app called Image Capture.

The app can be run from: Finder -> Applications -> Image Capture

Now, you can either download some or all photos by clicking on either one of the bottons as shown in the screenshot. Remember that you should have the iPhone connected to your copmuter, otherwise you would see the message saying the no device found or connected.

Remove Universal Access Preference icon from Gnome panel

Tue, 23 Jun 2009 10:48:35 +0000

One of the advantages of using GNU/Linux operating system is that you hardly have to restart it. I have Debian on my laptop and it’s been running for months, until last night. It crashed and froze. Anyway, that’s not the main point this post was written.

After restarting, I saw this new icon in the Gnome top panel (the third icon from the right):

Well, for the start, I don’t know what it is and I don’t think I will have a need for it either. So I wanted to remove it, but right click on this icon would do nothing. Left clicked on it would give me some setting option, but nowhere does it mention how to remove it.

C# Math.Round

Tue, 23 Jun 2009 01:35:42 +0000

This is just a quick note to remind myself:

 Math.Round(4.4); //Returns 4.0. Math.Round(4.5); //Returns 4.0. Math.Round(4.6); //Returns 5.0.

Credit: Math.Round Method

Pidgin 2.5.5 – cannot connect to Yahoo messenger

Sat, 20 Jun 2009 15:52:25 +0000

I just noticed the abnormality with Pidgin 2.5.5 (running on Debian) these few days — I couldn’t connect my Yahoo messenger account at all. According to the discussion of Bug #389278 it appears that Yahoo was trying to change its protocol.

A quick way to have Pidgin connecting to Yahoo messenger server again is to change the Pager server setting for the Yahoo account in Pidgin.

To do this, from Pidgin:

NHibernate.MappingException: Unknown entity class

Tue, 26 May 2009 06:11:33 +0000

If you get MappingException error, there are two things you should check out:

Make sure the name of the *.hbm.xml is spelled correctly — not *.hmb.xml nor *.mbh.xml
Make sure the Build Action property is set to “Embeded Resource.”

I learned this the hard way. First, I wrongly spelled hbm.xml and I had its Buld Action property set to “Content”. The above 2 points fixed the problem.

Credit: VerySimple, Inc

Debian JSON for Ruby

Sun, 24 May 2009 16:33:06 +0000

I tried to install JSON for Ruby via RubyGem,

# gem install json

and I got the following error message:

Building native extensions. This could take a while... ERROR: Error installing json: ERROR: Failed to build gem native extension.

/usr/bin/ruby1.8 extconf.rb install json extconf.rb:1:in `require': no such file to load -- mkmf (LoadError) from extconf.rb:1  Gem files will remain installed in /usr/lib/ruby/gems/1.8/gems/json-1.1.6 for inspection. Results logged to /usr/lib/ruby/gems/1.8/gems/json-1.1.6/ext/json/ext/generator/gem_make.out 

LoadError: no such file to load — openssl

Sat, 23 May 2009 13:22:15 +0000

On a Debian system, if the Ruby complains about “LoadError: no such file to load — openssl” try to install this package libopenssl-ruby

$ sudo apt-get install libopenssl-ruby

Now test if the problem resolved:

$ irb -rubygems irb(main):001:0> require 'openssl' => true

Voilla, there is no more load error.

Credit: Ruby Forum

apache2: Could not reliably determine the server’s fully qualified domain name, using 127.0.0.1 for ServerName

Tue, 10 Feb 2009 04:57:21 +0000

Everytime I start apache2 (# apache2ctl start) this message is dispalyed:

apache2: Could not reliably determine the server’s fully qualified domain name, using 127.0.0.1 for ServerName

Well, the site is still running despite the above notification.

To fix it, we need to edit the /etc/apache2/httpd.conf or /etc/apache2.conf and add the following line:

ServerName nameofserver

Now, restart the apache server (# apache2ctrl restart) and should no loger see the previous message.

Relocate the URL of SVN Repository

Fri, 06 Feb 2009 04:23:19 +0000

Recently, SVN has been installed on a local Debian box at work. This could have been done a bit earlier in my opinion, but well it’s better be a little late than never.

The SVN server is accessed via a LAN ip: 192.168.0.126. Because we didn’t setup static IP on the router, the IP of the server keeps changing from time to time. Here’s how one can change or relocate to the new URL.

HOWTO add user to sudoers list in Debian/Ubuntu

Tue, 27 Jan 2009 01:26:48 +0000

You need to have root access to do that. So the first step to become root with the following command:

ken@debian:~$ su Password: debian:/home/ken# visudo 

Now you can add a username to the list. For example:

 ken ALL=(ALL) ALL 

Save the file to complete the process.

Credit: Ubuntu Forum

Backup & Restore MS SQL 2000 Database

Thu, 15 Jan 2009 00:21:50 +0000

This is a ~~short~~ note I used at work to back up and restore the a MS SQL 2000 database.

I have a database with the name abcengine running on a local SQL Server. I need to back up this datbase to a file, send it over to a remote SQL Server to restore it.

There are two ways, which I’ve known, to back up a database. One of them is to use the Enterprise Manager to virsually back up, and another way is to use the Query Analyzer, writing the T-SQL code and run it.

Python MySQLdb package for Debian

Sun, 09 Nov 2008 14:40:10 +0000

I try to use MySQLdb module with my Python code for the first time. This is what I see:

import MySQLdb
Traceback (most recent call last):
File "", line 1, in
ImportError: No module named MySQLdb
your code here

For Debian, the package for MySQLdb module is python-mysqldb.

# apt-get install python-mysqldb

Now, let’s verify if MySQLdb module has been correctly installed:

>>> import MySQLdb
>>>

No more import error message, which means you can start using MySQldb module now.

IIS7 - Cannot read configuration file due to insufficient permissions

Thu, 23 Oct 2008 00:52:20 +0000

The last time I intensively used IIS (Internet Information Services) was back in the year 2000 when I hosted a ASP site on the local Windows 2000 server. Since then, Apache has become my only friend in the web server world.

Fast forward to present day with the current job where Microsoft technology is heavily based on, it’s time for me to get back on track with “almost-everything” Microsoft.

Today, I tried to set up an Asp.net site on my local machine with IIS7, and I got the following error:

Deleted folder keeps reappearing

Fri, 11 Jul 2008 13:51:37 +0000

A while back, I let my brother using my laptop while he was waiting for his to arried from online order. My laptop has dual boot: Windows Vista Home Premium and Debian. Of course, my bro would only use Vista. He created a folder with his name on the desktop for whatever purpose it was. Let’s called it: Evil.

When the laptop was returned to me, I wanted to get rid that Evil. No matter how many times I tried delete it, it kept coming back. I turned to Google for solution hoping someone on the Interweb experienced the same thing, but it wasn’t helpful either.

Visual Studio Shortcuts

Tue, 17 Jun 2008 06:19:24 +0000

This is an ongoing list of shortcuts used in Visual Studio 2005.

Go To Definition: Ctrl + F12
Go to line number: Ctrl + G
To comment a block of code: Ctrl + E + C
To uncomment a block of code: Ctrl + E + U

SQL Setup error on Vista: SQL Server Setup Failed to compile MOF

Tue, 13 May 2008 06:38:20 +0000

I was attempting to install MS SQL Server 2005 Express edition without success on a computer run Windows Vista Business. There was an error message mentioned “…failed to compile the Managed Object Format (MOF)…” I’ve tried about five times with various solutions; still it didn’t fix the problem.

As always, I found a working solution when I was about to give up on this installation. The problem was that the WMI repository was corrupted. There are two ways to fix this: one is to reinstall the WMI, and alternatively you can repair it instead.

Eterm doesn’t display “ or ”

Thu, 08 May 2008 01:27:23 +0000

Eterm doesn’t display the fancy “ or ” on my Debian. It is not a big problem, but it’s very annoying when it doesn’t properly display these symbols used in some programs such as aptitude.

I wanted to fix it, but didn’t realize it there was a fix. After two years or using it, I tried to find the solution again, and I found it. Just add the this code to the .profile in your home directory.

Enable mod_userdir for Apache2 on Debian

Tue, 22 Apr 2008 13:36:48 +0000

By default Apache2 doesn’t enable mod_userdir, a module to enable all users in your Linux system to host web pages. On Debian, it’s very to enable this mod, and probably with other modules as well. There is no need to edit the config file manually.

There are two tools offered by Debian to assist you with enabling and disabling the modules in Apache2: a2enmod and a2dismod. As the name inferred, a2enmod enables the modules, while the a2dismod does the opposite.

Debian enable/disable services

Wed, 02 Apr 2008 14:11:05 +0000

Install rcconf if you don’t have it yet. rcconf is Debian’s runlevel configuration tool. It allows you to enable or disable the services from starting up automatically. Recently, I got annoyed by postgresql starting up at boot time, so this tool did the trick.

Source: http://www.cyberciti.biz/faq/howto-runlevel-configuration-tool-to-start-service/

Vista Doesn't Recognize USB Drive

Sat, 26 Jan 2008 16:18:04 +0000

Recently my brother’s laptop which runs Windows Vista home premium no longer recognizes any USB drive. Every time a USB drive is connected to the laptop, it asks to install the drivers for that device. A while back at my part-time work place, a customer returned a laptop because it stopped recognizing the USB thumb drives.

The good news is I found the solution (from the Internet) on how to fix this problem. The file INFCACHE.1 in C:\windows\inf could be corrupted which is the main cause of the problem.

Fixed: /usr/lib/libdb-4.5.so: no version information available

Mon, 22 Oct 2007 15:15:59 +0000

After installing XEmacs, and ran it in terminal-mode, I got this error:

$ xemacs -nw
xemacs: /usr/lib/libdb-4.5.so: no version information available (required by xemacs)

The XEmacs works fine despite producing that error message. However, I want to get rid of it. Who or what do you turn to when you have problem with computer in general? Google search is your friend.

Here is the possible cause of the above problem. XEmacs require the newer version of lbdb-4.5 than the one installed on my Debian Lenny. At the time of this writing, the version of libdb4.5 on Lenny is 4.5.20-1. To fix this problem, you need to download the Sid version (4.5.20-9) and install it manually:

Start emacs in terminal-mode

Mon, 22 Oct 2007 12:04:38 +0000

The first text-editor in Linux I ever used was pico. Then I was introduced to emacs and remained using for awhile. Nowadays, vi(m) is my favorite and default text editor of choice. Anyway, the main point of this post is to how to start emacs in terminal-mode instead of graphical mode.

$ emacs -nw

That’s it. -nw actually does the trick.

Reference: How to get started…

htop - an interactive process viewer for Linux

Sun, 21 Oct 2007 14:54:10 +0000

Just browsed around through Linux blogs and I came across an interesting tool “htop” posted at Linux and Open Source Blog.

What is htop? It’s an interactive process viewer for Linux. It’s very similar to top, however htop enables you to scroll the list vertically or horizontally; as well as supporting mouse operation.

To install htop on Debian/Ubuntu distros, run this command:

$ sudo apt-get install htop

For openSUSE 10.2, you probably can install it with Yast, but I like smart:

Restore MySQL config file

Mon, 01 Oct 2007 15:49:40 +0000

I have installed mysql-server on my laptop running Debian back in awhile. For that reason, I forgot the root password. Just recently, I need to use MySQL server for one of my assignments. So, I was playing around in /etc/mysql/ directory hoping that I could get rid of the server and then reinstall it. The commands apt-get remove mysql-server didn’t seem to remove files/directories related to MySQL. Then, I decided to delete the /etc/mysql/ manually.

Install OpenOffice Khmer Spell Checker on Debian

Fri, 07 Sep 2007 02:52:26 +0000

Finally, the amazing team from KhmerOS has realeased the Khmer Spell Checker (KSC) for OpenOffice. Here is the instruction for installing KSC on Debian (Lenny) system.

Download the package from: http://sourceforge.net/project/showfiles.php?group_id=133361&package_id=244774
Unzip it:
```
$ unzip Khmer_Spellchecker_v1.0.zip
```
Change to that directory:
```
$ cd Khmer Spellchecker v1.0/
```

Become the super user:

$ su
Password: (enter your root password)

Copy two files: km_KH.aff km_KH.dic to OOo’s dict directory:
```
# cp km_* /usr/lib/openoffice/share/dict/ooo
```
The above directory could be slighty different from one system to another.

Resume broken download with Wget

Wed, 05 Sep 2007 14:24:16 +0000

$ wget -c http://www.example.com/files.iso

The -c(ontinuous) option allows Wget to resume a partial download.

Source:

Tomcat 6 on Debian Lenny

Tue, 14 Aug 2007 08:39:36 +0000

I need to install Tomcat 6 for a school assignment. I thought the installation process was easy as counting 123, but it turned out to be a few hours long of head scratching. Well, the first start is to setup a few environment variables as required by Tomcat:

CATALINA_BASE=/home/kenno/bin/apache-tomcat-6.0.13
CATALINA_HOME=/home/kenno/bin/apache-tomcat-6.0.13
export CATALINA_HOME;
export CATALINA_BASE# JAVA_HOME and Path to java, javac
JAVA_HOME=/usr/lib/j2sdk1.6-sun/bin
export JAVA_HOME;
export PATH=${JAVA_HOME}/bin:${PATH}:.

It can be stored in a setEnv.sh file, and run with source setEnv.sh to load those variables.

Bash Command Shortcuts

Wed, 04 Jul 2007 08:24:44 +0000

How many times do you find yourself using the arrow keys to move to the beginning or end of the command line in a bash terminal? Do you use backspace to delete every single character to clear what you’ve typed? If you answered “yes” to either of these questions, continue reading.

I have been doing this a lot myself because I couldn’t remember the shortcut keys for these tasks. So, I decided to write them here for future reference. While you can easily find more thorough information on the web, here are some useful shortcuts.

Installing Pidgin on openSUSE 10.2

Sun, 10 Jun 2007 15:51:16 +0000

If you’ve been using Gaim in the past, you probably know that it is no longer available now. The name of the program has been permanently changed to Pidgin. Even though Pidgin has been released for awhile, I’ve been still running Gaim Beta 2 until tonight. Well, not that I don’t want to install Pidgin, I just didn’t know how to do it. I tried to search for Pidgin openSUSE binary package in Google in the past for a few times without any success.

How to kill defunct process

Wed, 04 Apr 2007 00:15:14 +0000

Defunct processes are corrupted processes that can no longer communicate between the parent and child one. Sometimes, they become “zombies” and remain in your system until you reboot your machine. You can try to apply “kill -9” command, but most of the time you’ll be out of luck.

In order to kill theses defunct processes, you have two choices:

Reboot your computer
Continue reading…

First, let’s find out if the system contains defunct process:

Airport Extreme and Fedora Core 6

Fri, 09 Mar 2007 12:17:56 +0000

Ever since Fedora Core 6 was installed on my PowerBook, I can only access the Internet via ethernet port. It is a not a big problem at home, however if I want to access my university’s network or the Internet from there, the Wireless access is the only way. There is almost no where on campus or in the lab that I could hook the ethernet cable in. So everytime I want to access the network there, I have to boot into Mac OS X.

Enable Right-click & Middle-click with Fedora Core 6

Sat, 03 Mar 2007 14:53:46 +0000

The title should have been “How to enable right-click and middle click of PowerBook G4’s one-button-mouse in Fedora Core 6”. Since I’m not very keen in selecting a good title, I hope the one I wrote above made sense.

My Apple PowerBook G4 comes with just one button mouse. It’s not a problem when using it in OS X because I can simply emulate the right click by holding “fn” key while clicking. Recently, I just installed Fedora Core 6 as dual boot on this laptop; and one button mouse really gave me a big headache. I’ve beent trying to look for a good solution to fix this, but I didn’t get much luck. There were a few links on some blogs reporting that they had successfully solving this mouse problem by using something called “synaptic” driver, but that didn’t work for me either. The temporary solution was to use the USB mouse.

មេរៀនទី២៖ បីជំហានដើម្បីបង្កើតយ៉ាវា

Mon, 19 Feb 2007 11:36:19 +0000

នៅក្នុងមេរៀនមុន យើងបានឃើញឧទាហរណ៍កម្មវិធីតូចមួយ សរសេរជាមួយយ៉ាវា។ យើងបានបញ្ចប់មេរៀន ដោយចោលសំនួរថា “ហេតុអ្វីក៏យើងជ្រើសបំបែកកម្មវិធីដ៏តូចនោះជាពីរឯកសារ?” តាមពិតទៅ វាពុំមានជាអ្វីសំខាន់ ណាស់ណាទេ វាគ្រាន់តែជាការគិតថា បើធ្វើយ៉ាងនោះ វាមានផ្តល់ភាពងាយស្រូល ក្នុងការពិនិត្យកូតដើម។

យ៉ាវាកូតដើម (source code) តែងតែមាន ចុងកន្ទុយ (extension) .java ហើយឈ្មោះរបស់ឯកសារនោះ គួរចាប់ផ្តើមដោយអក្សរធំ ដោយ convention។ ចំនុចសំខាន់មួយទៀតដែលគួរគាត់ចំណាំគឺ ឈ្មោះរបស់ឯកសារត្រួវតែដូចនឹងឈ្មោះរបស់ class ។ បើសិនឃ្លាចុងក្រោយនេះមិនមានន័យចំពោះអ្នក សូមកុំទាន់បារម្ភ អ្វីៗនឹងបានច្បាស់លាស់ក្នុងពេលអនាគត។

ជាសង្ខេប ដើម្បីបង្កើតកម្មវីធិយ៉ាវា យើងត្រូវធ្វើតាម ៣ ដំណាក់កាល៖

១) សរសេរកូតដើម (source code)

២) កំផាយកូតដើម

៣) បញ្ជាកូដដែលបានកំផាយរួចហើយ (Execute or run the compiled program)

មេរៀនទី១៖ យ៉ាវា ភាសាកុំព្យូទ័រសំរាប់សរសេរកម្មវីធី

Sat, 17 Feb 2007 14:35:27 +0000

នៅក្នុងមេរៀនដំបូងនេះ យើងសន្មតថាលោកអ្នកបានបញ្ចូលយ៉ាវាកំផាយលើរទៅក្នុងមាស៊ីនកុំព្យូទ័រ

រួចហើយ។ ដូច្នេះ យើងអាចចាប់ផ្តើមសរសេរកម្មវិធីដំបូងបំផុត ដែលជាកម្មវីធីដ៏ល្បីល្បាញជាងគេគឺ “Hello World”។

public class MyApplication {
   public static void main(String[ ] args) {
      HelloWorldProgram p = new HelloWorldProgram();
      p.start();
   }
}

សរសេរកូតដូចខាងលើ ហើយផ្ទុកវាជាឯកសារឈ្មោះ MyApplication.java

បន្ទាប់មក សូមសរសេរកូចដូចខាងក្រោមនេះ ហើយផ្ទុកវាជាឯកសារមួយទៀតឈ្មោះ HelloWorldProgram.java

public class HelloWorldProgram {
   public void start() {
      System.out.println("Hello World");
   }
}

យើងកំផាយ (compile) ឯកសារទាំងពីរនោះដោយវាយពាក្យបញ្ជា៖

$ javac HelloWorldProgram.java
$ javac MyApplication.java

យើងអាចរត់ (run) កម្មវីធីដោយ៖

$ java MyApplication

បើសិនជាអ្នកមានចម្ងល់ថា ហេតុអ្វីក៏យើងចាំបាច់បំបែកកម្មវិធីដ៏តូចនេះជាពីរចំនែក?

Compiling C# Souce Code as a Dynamic Link Library

Fri, 16 Feb 2007 13:50:27 +0000

The following is the command to compile dllsource.cs as a dynamic link library instead of the executable file:

$ mcs /target:library dllsource.cs

We can also specify a different name of the binary with the /out option. For example:

$ mcs /target:library /out:mylibrary.dll dllsource.cs

Finally, if we want to compile a souce which depends on a dll file, we need to use the /reference option.

$ mcs example.cs /reference:mylibrary.dll

Note: mcs is the mono compiler. If you use Microsoft C# compiler, just replace mcs with csc.

Sum of elements in list in Prolog

Sun, 04 Feb 2007 13:06:30 +0000

Recently I noticed that my prolog skill is becoming rusty for not putting it work for very long. For this reason, I’m going to randomly write some prolog snippets here and there. Let’s started with one predicate called “sum_list” which calculate the value of all elements in a list.

% The sum of all elements in list in prolog

% empty list
list_sum([], 0).

list_sum([Head | Tail], TotalSum) :-
        list_sum(Tail, Sum1),
        TotalSum is Head + Sum1.

To run/test the above code, save it to a file called: list_sum.pl, fire-up your prolog interpreter and load it. In my case, I use swi-prolog. Here is the sample output:

ចងក្រង RPM ពី Source RPMs

Tue, 19 Dec 2006 09:37:18 +0000

ជាធម្មតា ពេលខ្ញុំបញ្ចូល កញ្ចប់ថ្មីៗក្នុងអូផិនស៊ូស៊ី បើសិនជាមិនអាចរក binary rpm បានទេ ខ្ញុំតែងតែចងក្រង (compile) កញ្ចប់ទាំងនោះពីកូដប្រភពដើម។ កូដប្រភពដើម អាចត្រូវបានខ្ចប់ជា tar.gz ឬ .src.rpm។ ក្នុងករណីទីមួយ យើងគ្រាន់តែពន្លា កូដប្រភពដើម រួចបញ្ជា ./configure, make និង make install ជាធម្មតា។ ពេលនេះ ខ្ញុំសូមលើកយក វិធីចងក្រងកម្មវិធី ជាមួយនឹង កូដប្រភពដើម ខ្ចប់ជា .src.rpm។

$ rpmbuild -clean -rebuild packagename.src.rpm

ក្រោយពីបាន វាយពាក្យបញ្ជាខាងលើហើយ កញ្ចប់ binary RPM នឹងត្រូវបានបង្កើតក្នុង subdirectory នៃ ថត /usr/src/packages/RPMS/។ សូមពិនិត្យមើល ក្នុងថតដែលមានឈ្មោះ ចាប់ផ្តើមដោយអក្សរ i\*** ឧទាហរណ៍ i386 ជាករណីរបស់ម៉ាស៊ីនខ្ញុំ។

Enable Khmer Unicode support on Firefox

Wed, 13 Dec 2006 16:04:44 +0000

With fresh installation of SuSE Linux 10.1 or openSUSE 10.2, Firefox does not display Khmer Unicode font properly. However, there is a very easy fix, all you have to do is to add the “MOZ_ENABLE_PANGO=1” to your .profile.

Go to your home directory, then edit the .profile file. I use vi (vi .profile)
Scroll down to the last line of the file and add: export MOZ_ENABLE_PANGO=1
Save the .profile file, in my case I do (ESC, SHIFT+Z+Z). Restart the Firefox.

Voilla! It’s done and the Firefox should display Khmer Unicode font nicely and correctly now.

ស្ថាបនា និង ដំឡើង បានស៊ី លើ ស៊ូសាលីណាក់ ១០.១

Wed, 06 Dec 2006 13:53:37 +0000

ដោយ Magnus Hoglund

ប្រសិនបើលោកអ្នកបានដំឡើង កំណែចាស់របស់បានស៊ី សូមចាប់ផ្តើមដោយលុបវាជាមុនសិន។
ដំឡើងកញ្ចប់ទាំងនេះ (ដោយប្រើ Yast)៖

mono-develop
monodoc-core
sqlite-devel
libmusicbrainz-devel
gstreamer010-devel
libgnomeui-devel
gnome-desktop-devel
nautilus-cd-burner-devel

យកកំណែថ្មីបង្អស់របស់ បានស៊ី ពី http://banshee-project.org។ ក្នុងសាច់រឿងនេះ កំណែចុងក្រោយគឺ ០.១១.២។ ទាញយកឯកសារ៖

banshee-0.11.2.tar.gz banshee-offical-plugins-0.11.2.tar.gz

ស្រាយ បានស៊ី (banshee-0.11.2.tar.gz) ទៅថតបណ្តោះអាសន្នមួយ។

$ tar xzvf banshee-0.11.2.tar.gz

បើកស្ថានីយ៍មួយ ក្នុងថតនេះ ហើយរត់៖

$ ./configure
$ make

ប្តូរទៅជាឫស (su) រួចរត់៖

$ make install

ចេញទៅជាអ្នកប្រើធម្មតា និង ចាប់ផ្តើម បានស៊ី

$ /usr/local/bin/banshee &

ការដំឡើង plugins របស់ បានស៊ី អាចធ្វើបានដោយវិធីដូចគ្នា។ ក្នុងករណីរបស់ខ្ញុំ ខ្ញុំបានស្រាយ banshee-offical-plugins-0.11.2.tar.gz និងរត់ ពាក្យបញ្ជាដូចខាងលើ (មានន័យថា៖ ./configure; make; make install)នេះជាការស្រេច សូមរីករាយសប្បាយជាមួយបានស៊ី!

Play Midi file on Linux

Fri, 17 Nov 2006 10:20:29 +0000

If you want to play midi file on Linux, SuSE for example, you need the midi player. Amarok or some other players such as Banshee couldn’t play midi at all. I am not sure why, however, I found a command-line application called Timidity. It can be downloaded from http://download.opensuse.org/distribution/SL-10.1/inst-source/suse/i586/timidity-2.13.2-21.i586.rpm. Once installed, you can play it by issuing this command timidity file_name.midi.

Here is an example running timidity to play what4.midi:

kenno@localhost:~/> timidity what4.mid
Requested buffer size 32768, fragment size 8192
  
ALSA pcm &#8216;default&#8217; set buffer size 32768, period size 8192 bytes
  
Playing what4.mid
  
MIDI file: what4.mid
  
Format: 1 Tracks: 5 Divisions: 480
  
Sequence:
Track name: Track 1
Track name: Guitar 2
Track name: Track 3
Track name: Percussion
Playing time: ~26 seconds
Notes cut: 0
Notes lost totally: 0

Enjoy the midi tune!

F-Spot Crashed on SuSE 10.1

Fri, 17 Nov 2006 04:09:06 +0000

Ever since this SuSE 10.1 installed, I could never once run F-Spot. I couldn’t remember what is the version of F-Spot that originally comes with SuSE 10.1 CDs, but even that one didn’t work. So, I upgraded it to 0.1.1 (the latest version at the time of writing is 0.2.2), but the same problem still remained. This is how it looks like when I run the program:

kenno@localhost:~> f-spot
Starting new FSpot server
XXXXX
System.ArgumentNullException: Argument cannot be null.
Parameter name: s
in  System.Int32:Parse (System.String s)
in  MetaItem:get_ValueAsInt ()
in  FSpot.Database.Updater:Run (.Db database)
in  Db:Init (System.String path, Boolean create_if_missing)
in  FSpot.Core:.ctor ()
in  FSpot.Driver:Main (System.String[] args)
XXXXX
Starting new FSpot server
Starting new FSpot server
Starting new FSpot server
Starting new FSpot server

On KDE desktop environment, there is also a very good native photo management application called digiKam which I have been using to organize my photos. As most of my times have been spent on school related work, getting the F-Spot running on my Linux box has been a avery low priority. Having said that, I never forgot about it.

Format Hard Disk with ext3

Tue, 07 Nov 2006 07:07:01 +0000

ដោយសារខ្ញុំបានប្រើប្រាស់ប្រព័ន្ធប្រត្តិប័ត្រការ Windows ជាយូលង់ណាស់មកហើយនោះ partitions នៃ hard disks ភាគច្រើនជា ntfs។ ថ្ងៃនេះខ្ញុំចង់បំលែង ntfs partition មួយមកជាលីណាក់ ext3 partition វិញដោយសារ hard drive ក្នុងលីណាក់ស្ទើពេញហើយ។ តើយើង format partition ជាមួយលីណាក់ដោយរបៀបណា? គិតៗទៅ ខ្ញុំមិនដែលបានធ្វើពីមុនទេ។

ដំបូងខ្ញុំខំរកកម្មវិធី ដែលមកជាមួយ ខេឌីអ៊ី (KDE) តែរកមិនឃើញមានអាណាមួយសំរាប់ហ្វមមាត (format) សោះ។ ប្រហែលជាមាន tools ឬកម្មវិធីខ្លះដែលអាចហ្វមមាត ដើរលើខេឌីអ៊ី ហើយខ្ញុំមិនបានបញ្ចូលវា ដូច្នេះបើលោកអ្នកដឹងឈ្មោះកម្មវិធីទាំងនោះ សូមមេត្តាប្រាប់ផង។ យ៉ាងណាមិញ ខ្ញុំបានសំរេចចិត្តប្រើ command-line ដើម្បីហ្វមមាតវា។ ខ្ញុំស្ទើភ្លេចប្រាប់ថា ក្នុងប្រព័ន្ធលីណាក់ វាមានប្រភេទ partitions ជាច្រើន ដូចជា៖ Reiserfs (the default one that SuSE 10.1 uses), ext3, zfx,… ។ល។ ខ្ញុំជ្រើសយក ext3 ក្រោយពីបានធ្វើការស្រាវជ្រាវបន្តេចបន្ទួច ហើយចំពោះភាពខុសគ្នានៃប្រភេទ partitions ទាំងនោះ ខ្ញុំពុំអាចដឹងច្បាស់ទេ។

អូខេ ដោយពុំចាំបាច់និយាយច្រើនពេក នេះគឺរបៀបដែលខ្ញុំបានប្រើ៖

ការបង្កើត zip file ជាមួយលីណាក់/យូនិច

Sun, 05 Nov 2006 17:16:17 +0000

តាំងពីបានប្រើលីណាក់មក ខ្ញុំពុំសូវដែលបានបង្រួមឯកសារជាមួយ zipទេ ភាកច្រើនខ្ញុំបង្កើត gzip។ ហេតុអ្វី? គិតថា gzip វាស្រួលបង្កើតជាងនិងដោយសារតំរួវការនៅសាលាផងនោះ។ ប៉ុន្តែយើងក៏មិនអាចជៀសវាង មិនប្រើ zipសោះដែរ។ ឧទាហរណ៍ ថ្ងៃនេះ មិត្តរបស់ខ្ញុំម្នាក់សួរខ្ញុំពីរបៀបបង្រួមឯកសារទៅជា zip ខ្ញុំស្រាប់តែស្រឡាំងកាំងតែម្តង។ ខ្ញុំសាកធ្វើដូចនេះ៖

$ ls
dir1

$ zip file1.zip dir1
adding: dir1/ (stored 0%)

មើលទៅហាក់ដូចជាដំណើរការ តែតាមពិត ឯកសារដែលនៅក្នុង dir1 អត់បានបញ្ចូលក្នុង file1.zip ទេ។ ដូចស័ព្ទដង អោយតែមានការងើងឆ្ងល់អ្វីមួយនោះ ខ្ញុំតែងតែសាកស្វែងរកជាមួយគូកឹល។ នេះគឺជាការបញ្ជាសំរាប់បង្រួមឯកសារដែលត្រឹមត្រូវ៖

$ zip -r file1.zip dir1
adding: dir1/ (stored 0%)
adding: dir1/myimage.jpg (stored 0%)

ប្រភពដើម

លេងឌីវីឌីជាមួយស៊ូសេ១០.១

Fri, 03 Nov 2006 10:31:56 +0000

អត្ថបទខ្លីនេះនិយាយអំពី ការចាក់លេងឌីវីឌីដែលមាន encryption ដាក់បង្កប់ក្នុងឌីវីឌី ដើម្បីការពារយើង កុំអោយលួចចំលងទុក។ ចំពោះឌីវីឌីភាកច្រើននៅស្រុកខ្មែរ ទាំងឌីវីឌីដើមដូចជាឌីវីឌីខារ៉ាអូខេហាក់បីដូចជាពុំមាន encryption ទេ។

ប៉ុន្តែបើលោកអ្នកទិញឌីវីឌីរឿងអាគាំងដើមវិញ ៩៩% ពិតជាមានបង្កប់ encryption ជាមិនខាន។ ឧទាហរណ៍ ថ្ងៃនេះខ្ញុំបានខ្ចីរឿងគំនូជីវចលជប៉ុន ពីមិត្តម្នាក់មានចំនងជើង ខ្មោចក្នុងសំបកសែល (Ghost in the Shell)

ហើយ បានសាកចាក់ជាមួយ កាហ្វេន (Kaffeine) លើលីណាក់ស៊ូសសេ១០.១ ប៉ុន្តែ ជាការសោកស្តាយ វាពុំអាចចាក់បានឡើយ។

ក្រោយពីបានរុករកចំលើយជាមួយគូកឹលមក ទើបដឹងថាបញ្ហាដើមគឺមកពី ស៊ូសេអត់មាន libdvdcss ដែលជាបណ្ណាល័យ ចាំបាច់សំរាប់ ពន្លា encryption វិញ។

ដូច្នេះបើយើងចង់លេង ឌីវីឌីទាំងនោះបាន យើងត្រូវបញ្ចុល libdvdcss ដែលអាចទាញយកបានពី នេះ ។ អាចបញ្ចូល ជាមួយនឹង ការបញ្ជានេះ៖

$ su -
password [enter root password]

# rpm -ivh libdvdcss2-1.9-i386.rpm

សូមសាកល្បងចាក់ឌីវីឌីម្តងទៀតមើល តើលោកអ្នកមានបញ្ហាទៀតទេ?

Playback DVD on SuSE 10.1

Fri, 03 Nov 2006 10:03:55 +0000

In general, almost all DVDs you purchase or rent from the store have encryption embedded them to protect you from copying them. It sounds like a good idea to prevent the piracy. To play back those DVDs, we need the player that could decrypt the encryption back. It’s not problem to play them on Windows operating system, but it is with most Linux operating system such as SuSE 10.1, Debian, etc.

Kernel upgrading breaks my SuSE box

Thu, 02 Nov 2006 07:20:47 +0000

The other day, my SuSE 10.1 notifies that there were updates available including bug fixes and new kernel. I thought it might be convenient if I just click on select all, and update button. So, I did that and went out to school. When I came back home, the update was nicely done. There was no indication to ask me to restart the computer (as most other OSes do), but I thought it’d be good restart it anyway.

Firefox 2.0 rpm សំរាប់ស៊ូសេ១០.១

Tue, 31 Oct 2006 15:10:18 +0000

ទោះបីជាFirefox 2.0បានបញ្ចេញប៉ុន្មានថ្ងៃមកហើយក៏ដោយ មិនមានអ្នកណាធ្វើកញ្ចប់ RPM សំរាប់ស៊ូសេលីណាក់ទេ។

ថ្ងៃនេះសំណាងល្អ ខ្ញុំបានទៅលេងទំព័រវ៉ិបនេះដែលនិយាយពីលីណាក់និងអូផិនសស់ ក៏ប្រទះឃើញដំណឹងទាក់ទងនឹង កញ្ចប់RPM

នៃFirefox 2.0សំរាប់ស៊ូសេ។

បើកុំព្យួទ័ររបស់អ្នកដើស៊ូសេលីណាក់ ហើយចង់បានFirefox 2.0 ដែរនោះ អ្នកអាចទៅទាញយកវាបានពី៖

SUSE 10.1 (i586) (១) | SLED 10 (i586) (២)

Firefox 2.0ក៏ត្រូវការ dependencies ពីរដែរ៖ mozilla-nss និង mozilla-nsrp។ អ្នកអាចទាញយកពួកវាពីរបណ្តាញខាងលើ។

ខ្ញុំទើបតែបានupdateរបស់ខ្ញុំថ្មីៗនេះ ហើយមានការពេញចិត្តជាមួយកំណែប្រែ២ នេះយ៉ាងខ្លាំង។ ខាងក្រោមនេះជារូប screenshot

Firefox 2.0 ដើរលើស៊ូសេ១០.១៖

(១) បណ្តាញសំរាប់ Open SuSE

(២) បណ្តាញសំរាប់ SuSE Linux Enterprise Desktop (paid version)

ប្រភពព៍តមាន៖ Linux and Open Source Blog

Disable sshd in SuSE 10.1

Thu, 17 Aug 2006 10:53:48 +0000

With the latest release of Open SuSE, version 10.1 at the time of writing, the ssh daemon (sshd) is turned on by default. Some sources on the web suggested that it doesn’t do any harms to have it on since it won’t be able to access from outside your LAN if the firewall is turned on. However, I think if you don’t need to use it, there is no point to leave it on.

Upgrade Amarok to 1.4.1

Sun, 13 Aug 2006 08:54:25 +0000

I’ve been using SuSE 10.1 for just about a month. The previous linux distro I used was Debian, so the rpm package concept is pretty new to me. I’ve heard of it before, but never got to use or play with it. With Debian, we have a very easy way to install or upgrade packages: apt-get, of course.

Anyway, I just upgraded the Amarok 1.3.8 to version 1.4.1. It wasn’t easy initially as I tried to upgrade each package of dependency separately. Fortunately, I found a good site that explains how to do this step by step. The following is the summary:

Vim Tip: Insert Time-Stamp

Thu, 03 Aug 2006 15:13:33 +0000

To insert time-stamp in a file, you can exit from edit mode and type:

:r! date

Apache 2 Config File

Sat, 15 Jul 2006 14:42:46 +0000

I’ve been using Apache httpd on and off on my PowerBook for various purposes including school assignments. The httpd version that comes with the PowerBook by default is 1.3.33 and I need to use the version 2.*. So, I installed the Apache 2 via Fink.

After having successfully installed Apache 2, we need to make some changes to the config file (usually, it is the httpd.conf file.) Guess what? I totally forgot where that file resides. The only thing I could remember is that we can find that information out very easily by giving the -v option to the httpd. So, I tried it and this is what I got:

UrlGenerator

Sat, 01 Jul 2006 11:58:21 +0000

I’ve been very bored, doing nothing interesting, and at the same time my programming skill is no longer as polished as before. I was kinda panic, and then I realize that if I don’t wanna lose the skill, I better continue coding. A while back, I wrote a code that generate the batch-link of website addresses. Example, I wanna grab all the images at a website from: http://www.example.com/image01.jpg to http://www.example.com/image10.jpg. In a simple way, we can just copy and paste, then change the number from 01 to 10. But what if you have to change the number from 001 to 100? Well, it’s gonna be tiresome. But, not if I use the program I wrote- UrlGenerator. It was a console program, written in Java. It doesn’t loo nice (as the matter of fact, it doesn’t have a look).

VS 2005 project is not rebuilt despite changes in source code

Tue, 27 Jun 2006 02:52:17 +0000

Having fixed a problem with Visual Studio (VS) 2005 the other day, there is still another problem. The project does not recompiled/rebuilt automatically after the souce codes of some files have been changed. Usually, if we make changes to the souce code, those files will be recompiled if we press Ctrl+F5 or F5.

At first I thought this could be the new behavior/feature in VS 2005. But after discussing with a buddy of mine who’s currently using VS 2005 for his assignment, he told me that VS 2005 should rebuild the code automatically.

"The Binding Handle Is Invalid" error in Visual Studio 2005

Sun, 25 Jun 2006 13:35:15 +0000

Tonight is the first time I began to code a small program in C# again since my graduation in April ‘06. It’s just because I was away from Windows PC, and it’s not easy do a GUI application with Mono on Mac. So it’s not that I hate C# or anything. Anyway, I just installed Visual Studio .Net 2005 Profession edition (non-commercial use) on my home PC, and I encountered a never-seen-before (to me at least) error straight away when I tried to debug/build the program. Well, google search pointed me to a solution to this problem.

My Linux Phone: e680i

Sat, 17 Jun 2006 14:03:29 +0000

After waiting about four or five months, I finally could get a hold of my new phone. The phone was purchased in Cambodia as a gift from my brothers. I would like to thank three of them who had put some efforts in making my wishes come true. In addition, a big thank also goes to my girlfriend for delivering the phone to me.

In fact, e360i phone is a pretty old model. It was manufactured by Motorola as one of their first mobile phones running Linux as the operating system. About a year a half ago, Ed, a friend of mine from New Zealand, introduced me to his phone. He urged that I should get one, as well as convinced me that this phone was way better than my Nokia ones. Guess what? I should have believed him, this phone is awesome, entertaining, functioning and butt-kicking. So, Ed, thank you a lot too dude, if you happen to read this post. I appreciate also that you spent time teaching me all the nice tip and trick about e680i.

VMware Installation – A Small Solution to a Huge On Going Problem

Tue, 06 Jun 2006 17:40:59 +0000

VMware is a piece of art of software which allows you to run guest operating stystems (OS) on top of the main OS you’re using. For example in my case, I run SuSE 10.0 on Windows XP via VMware. Anyway, despite having the name as cool as it sounds, installing the VMware on my machine is a pain in the rear.

This could explain why I so stated as above. The installation of VMware always gives the blue-screen-of-death on the Windows XP SP2 on the final step. Initially, I thought that some services running on my machine may cause the problem, so I disabled most of them. In addition, I also shutdown Zone Alarm, and all the running programs. Nothing helped at all. I remember, the last time I wanted to run VMware so bad, that I decided to reinstall the Windows XP.

LBreakout2 for Mac OS X

Fri, 21 Apr 2006 01:54:58 +0000

LBreakout2 is another multi-platform game written by the same programmer as LBreakout. The new features of the games include more than 50 levels, level editor and networking, which enables user to play on-line by connecting to LBreakout2 server. I haven’t tried that yet though. You can find more info at the LBreakout2 homepage.

Let’s check out the screen-shot:

A tip to compile this game for Mac OS X is to configure the source with the nls disable. I’m not very sure what nls is either if you ask me what it is. Anyway, if you wanna compile it for your Mac OS X, you need to get/do the following:

Compiling libpng for Mac OS X

Thu, 20 Apr 2006 01:12:16 +0000

I thought Mac OS X comes with libpng pre-installed. It’s pretty clear that I was wrong after I failed to compile a game that uses libpng. The good thing about OS X is that, you can just use fink to easily install Unix/Linux binaries. However, the weird thing is, the game configuration still complains that libpng could not be found.

So I decided to install libpng from the source code. For those out there who may face the same problem, you could try as what I describe below.

LBreakOut

Wed, 19 Apr 2006 06:15:04 +0000

I’m pretty bored today, and I wanna take a break from learning Python. So, I decided to compile an open source game, LBreakOut (L is for Linux), for my PowerBook.

In order to compile this game, you need obviously the source code of the game where you can get it from here. Additionally, you need the SDL library, where you can get it from http://www.libsdl.org.

Here is the screen-shot of game running on my PowerBook:

How to Decompress .tar.bz2 File

Tue, 18 Apr 2006 12:26:16 +0000

Normally, I would bunzip the file first, then untar it next. But I found something after googling for a shortcut: it can all be done with just one tar command.

$ tar -xjvf example.tar.bz2

Notice that, we use j flag to decompress bzip2 file and z flag for gzip file. 🙂

Temperature Conversion v0.2

Thu, 13 Apr 2006 13:41:17 +0000

I just learned how to implement basic command-line argument with Python. Hence, I would like to incoporate this feature in the previous Temperature Conversion program.

# convertc2f.py
# Version: 0.2
# A program to convert Celsius temps to Fahrenheit
# Date: 4/13/06
# by: S. San (Kenno)`

import sys

if (len(sys.argv) == 2):
    celsius = int(sys.argv[1])
else:
    celsius = int(input("What is the Celsius temperature? "))
 
fahrenheit = 9.0 / 5.0 * celsius + 32
print("The temparature is", fahrenheit, "degrees Fahrenheit.")

Example with the command line argument:

Using Java 5 on Mac OS X Tiger

Fri, 07 Apr 2006 04:11:38 +0000

Mac OS X Tiger still uses the J2SE 1.4 as default Java virtual machine and compiler. If you need to upgrade to JDK 5, you have to download it from Apple download site.

After you install it, you need to change a symlink to point to the JDK 5:

$ cd /System/Library/Frameworks/JavaVM.framework/Versions/ $ sudo mv Current Current.old $ ln -s 1.5 Current $ mv CurrentJDK CurrentJDK.old $ ln -s 1.5 CurrentJDK

Temperature Conversion

Thu, 06 Apr 2006 05:16:32 +0000

If you get used to read the temperature in Fahrenheit scale like me, you may be confusing to see the temperature in Celsius scale given in weather forcasting on Australian or New Zealand televisions.

So today, I’m gonna share a small Python program which can be used to convert the temperature scale from Fahrenheit to Celsius. As my Python programming skill is very limited at the moment, the program is going to perform very basic function.

Hello World – Python

Wed, 05 Apr 2006 04:58:59 +0000

I’ve been hearing a lot about “Python”, so I decided to pick up a book “Python Programming for Absolute Beginner” by Michael Dawson. Today, I’m going to share with you how to write classic “Hello World” program in Python.

Fire your favorite text editor program, in my case I use vim.

kenno$ vim helloworld.py

Then type the following code:

# Hello World print "Hello World!"

Save it, and execute it with the following command:

How to Decompress a bzip2 File

Tue, 04 Apr 2006 05:19:53 +0000

bunzip -v exampleFile.bz2

bzip2 -dv exampleFile.bz2

bzip2 -h
man bzip2
bzip2 homepage

Hello world!

Thu, 16 Mar 2006 11:26:09 +0000

I’m not too sure what to do with this blog yet. I’ll see if I should move my old blog from Blogspot to here, or just using both concurrently. Anyway, only time can tell. As for now I’m gonna try to explore the features of WordPress since I’m pretty new to this blog system.

However, if you wanna check out my old blog, here it is: Just Shoot It.