>Usage
grep (Global Regular Expression Print) is a powerful command-line tool that searches for specified patterns in files or text streams. It’s like having a digital magnifying glass that can find any text pattern you're looking for across one or multiple files.
>Synopsis
>Options
-i
-i (ignore case): Ignores case while searching for the pattern.
Example 1:
-zsh
> echo "Hello World" | grep -i "hello"
Hello World
!!! Grep normally reqires a file for input, but beacuse is allowed and for ease of explanations is used echo !!!
-r
-r (recursive): Searches files in directories and subdirectories.
Example 2:
-zsh
> grep -r "pattern" ./directory/
./directory/file.txt: pattern
-v
-v (invert match): Displays all lines that do not match the pattern.
Example 3:
-zsh
> echo -e "apple\nbanana\ncherry" | grep -v "banana"
apple
cherry
-l
-l (files with matches): Shows only the names of files that contain the pattern.
Example 4:
-zsh
> grep -l "error" *.log
error_log.txt
-n
-n (line number): Displays the line number along with the matching lines.
Example 5:
-zsh
> echo -e "line 1\nline 2\nline 3" | grep -n "line 2"
2:line 2
-w
-w (word match): Matches the exact word, not just a substring.
Example 6:
-zsh
> echo -e "apple pie\npineapple" | grep -w "apple"
apple pie
-c
-c (count matches): Counts the number of lines that match the pattern.
Example 7:
-zsh
> echo -e "apple\nbanana\napple" | grep -c "apple"
2
-o
-o (only matching): Outputs only the matched parts of the line.
Example 8:
-zsh
> echo "apple banana apple" | grep -o "apple"
apple
apple
-A
-A (after context): Shows a specified number of lines after the matching line.
Example 9:
-zsh
> echo -e "apple\nbanana\ncherry" | grep -A 1 "banana"
banana
cherry
-B
-B (before context): Shows a specified number of lines before the matching line.
Example 10:
-zsh
> echo -e "apple\nbanana\ncherry" | grep -B 1 "banana"
apple
banana