Cheat Sheet #day43

`grep` Cheatsheet

Basic Usage

Search for a Pattern in a File
```
  grep 'pattern' filename
```
Search for a Pattern in Multiple Files
```
  grep 'pattern' file1 file2 file3
```

Common Options

Ignore Case Sensitivity
```
  grep -i 'pattern' filename
```
Show Line Numbers
```
  grep -n 'pattern' filename
```
Search Recursively in Directories
```
  grep -r 'pattern' directory
```
Show Only Matching Part of the Line
```
  grep -o 'pattern' filename
```
Count the Number of Matches
```
  grep -c 'pattern' filename
```
Show Lines that Do Not Match the Pattern
```
  grep -v 'pattern' filename
```

Advanced Options

Search for Whole Words
```
  grep -w 'pattern' filename
```
Match the Pattern at the Beginning of a Line
```
  grep '^pattern' filename
```
Match the Pattern at the End of a Line
```
  grep 'pattern$' filename
```
Show N Lines of Context Before the Match
```
  grep -B N 'pattern' filename
```
Show N Lines of Context After the Match
```
  grep -A N 'pattern' filename
```
Show N Lines of Context Around the Match
```
  grep -C N 'pattern' filename
```

Useful Tips

Use Extended Regular Expressions
```
  grep -E 'pattern' filename
```
Use Fixed Strings (Faster for Simple Strings)
```
  grep -F 'pattern' filename
```
Show Only the Names of Files with Matches
```
  grep -l 'pattern' filename
```
Show Only the Names of Files without Matches
```
  grep -L 'pattern' filename
```
Display Help for grep
```
  grep --help
```
Search Using Perl-Compatible Regular Expressions
```
  grep -P 'pattern' filename
```
Colorize the Output
```
  grep --color=auto 'pattern' filename
```

Examples

Search for a Case-Insensitive Pattern in a File
```
  grep -i 'error' logfile.txt
```
Search for a Pattern in All Files in the Current Directory
```
  grep 'TODO' *
```
Search for a Pattern Recursively in a Directory
```
  grep -r 'TODO' /path/to/directory
```
Search for a Whole Word Only
```
  grep -w 'hello' filename
```
Search for a Pattern and Show Line Numbers
```
  grep -n 'main' script.py
```
Search for a Pattern and Show Only Matching Part of the Line
```
  grep -o 'http[s]*://[^ ]*' filename
```
Count the Number of Occurrences of a Pattern
```
  grep -c 'main' script.py
```
Search for a Pattern and Show 3 Lines of Context After the Match
```
  grep -A 3 'function' script.py
```
Search for a Pattern and Show 2 Lines of Context Before the Match
```
  grep -B 2 'error' logfile.txt
```
Search for a Pattern and Show 1 Line of Context Around the Match
```
  grep -C 1 'TODO' script.py
```
Use Extended Regular Expressions to Search for Multiple Patterns
```
  grep -E 'error|warning|info' logfile.txt
```
Search for a Pattern Using Perl-Compatible Regular Expressions
```
  grep -P '\d{3}-\d{2}-\d{4}' filename
```
Search for a Pattern in a Compressed File
```
  zgrep 'pattern' file.gz
```

This cheatsheet covers essential commands and options for using grep effectively, from basic searching to advanced pattern matching and context display. Adjust the commands according to your specific requirements and environment.

Cheat Sheet #day43 - grep

grep Cheatsheet