LINUX COMMAND ATLAS · COMMAND GUIDE

Linux grep command

Search text for a pattern. Use -R for directories and -n to show line numbers.

GNU Grep

Syntax

Command form

grep [OPTION]... PATTERN [FILE...]

8 options

Option	What it does
`-i, --ignore-case`	Ignore case distinctions.
`-n, --line-number`	Print line numbers with matching lines.
`-r, --recursive`	Search directories recursively (follow symlinks to files).
`-v, --invert-match`	Select lines that do not match.
`-E, --extended-regexp`	Interpret PATTERN as an extended regular expression.
`-F, --fixed-strings`	Treat PATTERN as a list of literal strings.
`-w, --word-regexp`	Match whole words.
`-l, --files-with-matches`	Print only names of files with matches.

3 examples

Search text for a pattern. Use -R for directories and -n to show line numbers.

grep -Rni "error" ./logs

Show matching lines and their line numbers.

grep -n 'error' app.log

Search .conf files recursively, ignoring case and showing line numbers.

grep -Rni --include='*.conf' 'timeout' ./config

Quote patterns containing shell characters. Use -F for literal text and -E when regular-expression syntax is intended.