Grep Commands Cheat Sheet

Options

-i: Ignore case (case-insensitive search)
-w: Match whole word
-n: Show line numbers
-c: Count the number of matching lines
-v: Invert match, show lines that do not match
-r: Search files recursively in subdirectories
-l: Show only the filenames of matching files
-h: Do not show filenames in output
-e pattern: Use pattern as the search pattern
-f file: Read the search pattern from a file
-E: Interpret the pattern as an extended regular expression
-P: Interpret the pattern as a Perl-compatible regular expression
-m num: Stop after finding num matches
-A num: Show num lines of trailing context after the match
-B num: Show num lines of leading context before the match
-C num: Show num lines of context before and after the match

Regular Expressions

.: Match any single character
^: Match the beginning of a line
$: Match the end of a line
[]: Match any character inside the brackets
[^]: Match any character NOT inside the brackets
(): Group characters together
|: Match either/or (e.g. cat|dog)
*: Match zero or more of the preceding character
+: Match one or more of the preceding character
?: Match zero or one of the preceding character
{}: Match a range of occurrences (e.g. a{1,3} matches "a", "aa", or "aaa")

Basic Text Search

Search for a pattern in a file

Search for a specific word or pattern: grep 'pattern' file.txt
Search across multiple files: grep 'pattern' file1.txt file2.txt
Search recursively in a directory: grep -r 'pattern' /path/to/directory/

Case Sensitivity

Perform a case-insensitive search

Ignore case when matching patterns: grep -i 'pattern' file.txt

Inverted Match

Exclude matching lines

Show lines that do not match the pattern: grep -v 'pattern' file.txt

Matching Whole Words

Match entire words only

Match only whole words in a file: grep -w 'word' file.txt

Display Context

Show surrounding lines for matches

Print 3 lines before each match: grep -B 3 'pattern' file.txt
Print 3 lines after each match: grep -A 3 'pattern' file.txt
Print 3 lines before and after each match: grep -C 3 'pattern' file.txt

Counting Matches

Count the number of matching lines

Display only the count of matching lines: grep -c 'pattern' file.txt

Line Number and File Information

Include line numbers or filenames

Display line numbers for matches: grep -n 'pattern' file.txt
Print filenames with matches: grep -H 'pattern' file.txt

Multiple Patterns

Search for multiple patterns

Match any of several patterns: grep -e 'pattern1' -e 'pattern2' file.txt
Use a file with multiple patterns: grep -f patterns.txt file.txt

Regular Expression Search

Enable extended regular expressions

Use extended regex patterns: grep -E 'pattern1|pattern2' file.txt

Use Perl-compatible regular expressions

Interpret patterns as Perl-compatible regex: grep -P 'pattern' file.txt

Output Customization

Highlight matches

Enable colored output for matches: grep --color=auto 'pattern' file.txt

Show only matched parts of lines

Print only the matching portion of lines: grep -o 'pattern' file.txt

Fixed String Matching

Match exact strings

Search using fixed strings (faster for literals): grep -F 'exact string' file.txt

File Searching

List files with matches

Print only the filenames containing matches: grep -l 'pattern' *.txt

List files without matches

Print filenames that do not contain matches: grep -L 'pattern' *.txt

Contextual Examples

Practical Applications

Search for lines starting with "Error":
grep '^Error' log.txt
Find lines ending with ".com":
grep '\.com$' emails.txt
Match lines containing digits:
grep '[0-9]' file.txt
Exclude empty lines:
grep -v '^$' file.txt