Kenno’s Open Note 👋

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Replacing cron with systemd timer

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....

September 3, 2024 · 3 min · 428 words · kenno

Upgrading Longhorn with Helm

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]....

August 23, 2024 · 4 min · 647 words · kenno

How to rebuild initramfs on Fedora

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....

August 21, 2024 · 5 min · 1000 words · kenno

Process Life Cycle

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....

August 3, 2024 · 2 min · 372 words · kenno

Snapshot of LVM logical volume - a brief howto

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....

July 26, 2024 · 3 min · 491 words · kenno