Linux server tutorials

9 of 45 tutorials in Linux basics tested on Ubuntu 24.04 LTS

1. Cron vs systemd timers: how to schedule jobs on Linux

   Schedule a recurring job both ways, with a crontab line and with a systemd timer, and pick the right one for logging, missed runs and random delays.

   beginner · 20 min · Ubuntu 24.04 LTS, Debian 13 Stable, AlmaLinux 10

2. How to create a sudo user and disable root login on Ubuntu and Debian

   Add a normal user with sudo rights on Ubuntu or Debian, give it your SSH key, then stop root logging in over SSH without locking yourself out.

   beginner · 15 min · Ubuntu 24.04 LTS, Debian 13 Stable

3. How to find what's using disk space on Linux and free it safely

   Find what filled your server's disk with df, du and ncdu, then safely clean package caches, logs, old kernels and deleted files still held open.

   beginner · 15 min · Ubuntu 24.04 LTS, AlmaLinux 10

4. How to read logs with journalctl

   Find the log lines you need with journalctl, by service, time, priority and boot, keep logs across reboots, and cap how much disk the journal uses.

   beginner · 15 min · Ubuntu 24.04 LTS, Debian 13 Stable, AlmaLinux 10

5. How to set the time zone, hostname and NTP on a Linux server

   Set a server's time zone with timedatectl, give it a proper hostname, and keep its clock in sync with chrony or systemd-timesyncd, then check it really is.

   beginner · 10 min · Ubuntu 24.04 LTS, Debian 13 Stable, AlmaLinux 10

6. Use curl and jq with the VPSNine API

   Drive the VPSNine API from a shell with curl and jq: filter servers, take snapshots and wait for them, read errors, page invoices, edit the firewall.

   beginner · 20 min · Ubuntu 24.04 LTS, Debian 12 Oldstable

7. How to troubleshoot high CPU and memory usage on a Linux server

   Find the process behind high CPU or memory use with top, ps, vmstat and pidstat, read load average and steal time correctly, and spot the OOM killer.

   intermediate · 20 min · Ubuntu 24.04 LTS

8. How to upgrade Ubuntu 22.04 to 24.04 LTS safely

   Upgrade an Ubuntu 22.04 server to 24.04 LTS in place with do-release-upgrade, with a snapshot first, a backup SSH port, and checks for what changes.

   intermediate · 45 min · Ubuntu 22.04 LTS, Ubuntu 24.04 LTS

9. How to write a systemd service for your app

   Run your own program as a systemd service that starts at boot, restarts when it crashes, runs as its own user, reads an env file and is sandboxed.

   intermediate · 20 min · Ubuntu 24.04 LTS, Debian 13 Stable, AlmaLinux 10