The grep command in Linux explained
The grep command searches text for lines that match a pattern. It is one of the most useful commands for anyone using a live USB drive or a fresh Linux install.
Syntax
grep [options] pattern file
Examples
grep error log.txt: lines containing the word errorgrep -i -r "usb" /etc: case-insensitive search through a folder
Tip
You can pipe other commands into it, for example lsusb | grep SanDisk.
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 grep in a terminal for the full manual.
Frequently asked questions
How do I see every option for grep?
Run man grep for the full manual, or try grep --help for a short summary.
Do I need sudo to run grep?
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 grep 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.