grep

Search for pattern in file

$ grep [pattern] [file]

$ grep -i [pattern] [file]

$ grep -r [pattern] [directory]

$ grep -n [pattern] [file]

$ grep -v [pattern] [file]

$ grep -E '[regex]' [file]

$ grep -c [pattern] [file]

grep [options] pattern [files]

grep searches files for lines matching a pattern. It's one of the most fundamental Unix utilities, named for g/re/p (global regular expression print) from ed.
The tool supports basic and extended regular expressions, recursive directory searching, and various output formats. It can search multiple files, show context around matches, and highlight results.
grep is essential for text searching and filtering.

PATTERN

Regular expression pattern to match.

Files to search.

Case insensitive matching.

Select non-matching lines.

Search directories recursively.

Show line numbers.

Print match count only.

Print only filenames.

Use extended regex.

Match literal strings.

Print only matched parts.

Print NUM lines after match.

Print NUM lines before match.

Print NUM lines of context.

Highlight matches.

Display help information.

Basic vs extended regex syntax differences. Binary files may produce unexpected output. Large files may be slow without optimizations.

grep was created by Ken Thompson at Bell Labs in 1974. It was inspired by the g/re/p command in ed. GNU grep is the most widely used implementation today.

egrep(1), fgrep(1), rg(1), ack(1), sed(1)