Centos7 on Kenno's Open Note

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'.

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:

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: