Linux grep command

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

Availability: Common Linux commands; shell built-ins and external implementations may differ by distribution.中文

Syntax

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

Examples

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

Parameters, options and clauses

Option / clause	Description
`-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.

Safety note

Review a command and its target before running it. Commands that alter files, services, accounts, disks, permissions or databases may be difficult to reverse. Test in a safe environment and keep backups.

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