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System administration

Seven lessons on looking after a Linux machine or server: users and sudo, installing software, services and logs, memory and disks, networking, SSH with keys, and scheduled jobs and backups.

  1. Users and groups

    Add and remove users, set passwords, give someone sudo, and where Linux keeps the user list.

    6 questions

  2. Installing software

    Package managers: install, update and remove software with apt or dnf, and keep the system patched.

    6 questions

  3. Services and logs

    Start, stop and enable background services with systemctl, and read their logs with journalctl.

    6 questions

  4. Memory, disks and load

    Check memory with free, disks with df and lsblk, and what load average and the OOM killer mean.

    6 questions

  5. Networking

    Your address with ip, testing with ping and curl, which ports are open with ss, and a simple firewall.

    6 questions

  6. SSH

    Log in to another machine, set up keys instead of passwords, copy files across, and lock it down.

    7 questions

  7. Scheduled jobs and backups

    Run commands on a timetable with cron, read the five time fields, and back up with rsync and tar.

    7 questions
More info

How it works

Each lesson is a short read with real commands and what they show, then a few practice questions. Some have you type the command for a job, some have you pick an answer, and some have you tap steps into the right order. Typed commands are checked exactly as the shell would read them, capitals included, and most have more than one right way. You can try again as often as you like; after two misses there’s a button to show the answer.

What do I need to know first?

The other three Linux courses, or being at home on the command line. The commands are for Ubuntu and Debian (apt) with the Fedora and Red Hat ones (dnf) alongside.

The other Linux courses

Where is my progress saved? In this browser, like the rest of the site. Nothing to sign up for.

Linux® is the registered trademark of Linus Torvalds in the U.S. and other countries. This course isn’t made by or affiliated with him or the Linux Foundation.