Linux

Linux is a Unix-like operating system kernel first released by Linus Torvalds in 1991. The name is also used for the whole family of systems built around it, packaged as distributions such as Debian, Ubuntu, and Fedora.

Why it matters

Linux runs a large share of web servers, cloud instances, routers, and embedded devices, and Android uses a modified Linux kernel. If you host a website, it very likely sits on a Linux machine, so basic Linux skills are part of diagnosing outages.

Its license allows anyone to inspect, modify, and redistribute it, which is why so many variants exist.

Example

$ cat /etc/os-release
PRETTY_NAME="Debian GNU/Linux 12 (bookworm)"
$ systemctl status nginx

The first command shows which distribution you are on. The second checks whether the web server service is running.

Common mistakes

• Assuming all Linux systems behave the same. Package managers, paths, and defaults differ by distribution.
• Using the root account for daily work instead of a normal user with sudo.
• Believing Linux needs no patching because it is rarely targeted.

Related

• Linux Distribution (Distro)
• Kernel
• Bash
• chmod (File Permissions)

This page is general information written by our editorial team and updated when documentation changes. Servers and providers differ, so test changes safely first. See our editorial policy and disclaimer.