Grep Command Cheatsheet

Basic Operations

Basic search syntax and common options.

``bash # Search for string in file (case-sensitive) grep "error" app.log

# Case-insensitive search grep -i "error" app.log

# Show line numbers grep -n "error" app.log

# Invert match (show non-matching lines) grep -v "debug" app.log

# Match whole words only grep -w "error" app.log

# Match whole lines only grep -x "ERROR: Connection timeout" app.log

# Count matching lines grep -c "error" app.log

# Show only filenames with matches grep -l "error" *.log

# Show filenames without matches grep -L "error" *.log

# Output only matched parts grep -o "[0-9]\\+" app.log

# Limit number of matches grep -m 5 "error" app.log

# Quiet mode (exit code only) grep -q "pattern" file && echo "Found" `

Recursive Search

Search recursively through directory trees.

`bash # Recursive search in current directory grep -r "TODO" .

# Recursive search (follow symlinks) grep -R "TODO" /etc/

# Show filenames only grep -rl "function" src/

# Show filenames without matches (inverse) grep -rL "error" logs/

# Read patterns from file grep -f patterns.txt target.log

# Count matches per file grep -rc "import" src/

# Search multiple patterns grep -e "ERROR" -e "FATAL" app.log

# Combine with find find . -name "*.py" -exec grep "def " {} + `

Context Control

Display context around matching lines.

`bash # Show 2 lines after match grep -A 2 "Exception" stacktrace.log

# Show 2 lines before match grep -B 2 "ERROR" app.log

# Show 3 lines before and after grep -C 3 "timeout" app.log

# Group results with -- separator grep -C 2 "error" log.txt

# Highlight matches grep --color=always "pattern" file `

Regular Expressions

Using extended and Perl-compatible regular expressions.

`bash # Extended regular expressions (ERE) grep -E "[0-9]{3}-[0-9]{4}" phone.txt

# Perl-compatible regex (PCRE) grep -P "\\d{3}-\\d{4}" phone.txt

# Start of line grep "^ERROR" app.log

# End of line grep "done$" build.log

# Character class grep -E "gr[ae]y" colors.txt

# Any single character grep "f..l" words.txt

# Repetition grep -E "go+" pattern.txt

# Optional character grep -E "colou?r" colors.txt

# Specific count grep -E "\\d{3,5}" numbers.txt

# Word boundary grep -E "\\berror\\b" text.txt

# Logical OR grep -E "cat|dog|bird" animals.txt

# Ignore binary files grep -I "text" binary_file `

Output Control

Formatting and managing grep output.

`bash # Show filename (default with multiple files) grep -H "pattern" file1 file2

# Suppress filename grep -h "pattern" file1 file2

# Null-delimited output (for xargs -0) grep -rlZ "pattern" . | xargs -0 rm

# Colored output (always/auto/never) grep --color=auto "pattern" file

# Quiet mode, check existence only grep -q "pattern" file && echo "exists"

# Aligned output with tab separator grep -n "pattern" file

# Pipe to other commands grep "error" app.log | cut -d' ' -f1

# Chain multiple greps grep "ERROR" app.log | grep -v "timeout" | head -20

# Search command history history | grep "docker"

# Combine with wc grep -c "pattern" file.log

# Combine with sort and uniq grep -o "\\b[A-Z]\\+\\b" file | sort | uniq -c | sort -rn `

File Filtering

Control which files and directories grep searches.

`bash # Search only specific file types grep -r --include="*.py" "class" .

# Include multiple file types grep -r --include="*.{js,ts}" "import" .

# Exclude specific files grep -r --exclude="*.min.js" "function" .

# Exclude files listed in a file grep -r --exclude-from=ignore.txt "pattern" .

# Exclude directories grep -r --exclude-dir=node_modules "require" .

# Exclude multiple directories grep -r --exclude-dir={node_modules,.git,dist} "pattern" .

# Search only matching glob grep -r --include="*.log" "ERROR" /var/log/

# Search binary files (show text portions) grep -a "text" binary.exe

# Skip binary files grep -rI "pattern" . ``