The chmod command in Linux explained
The chmod command changes who can read, write or run a file. It is one of the most useful commands for anyone using a live USB drive or a fresh Linux install.
Syntax
chmod [mode] file
Examples
chmod +x script.sh: make a script runnablechmod 644 notes.txt: owner reads and writes, others read
Tip
In numeric modes, read is 4, write is 2 and execute is 1.
Keep learning
New to the terminal? Start with Linux terminal basics. You can try every command safely from a live session: see how to try Linux without installing it. Run man chmod in a terminal for the full manual.
Frequently asked questions
How do I see every option for chmod?
Run man chmod for the full manual, or try chmod --help for a short summary.
Do I need sudo to run chmod?
Not for your own files. You only need sudo when the command changes something owned by the system or another user.
Is it safe to practise chmod on a live USB drive?
Mostly yes, because a live session starts fresh each time. Be careful with commands that write to your internal disk, such as rm on a mounted drive or dd.