grep
grep is like a search-and-highlight tool that reads through lines of text and shows you only the ones that contain the word you are hunting for.
In this page:
Syntax
grep [-i] [-n] [-v] "pattern" file_namegrep
grep searches input for lines matching a pattern and prints the matching lines. Common flags include -i (case-insensitive), -v (invert match), -n (show line numbers), and -r (recursive over a directory).
It's one of the most frequently used text-processing tools in shell scripting.
Note:
grep -v pattern prints every line that does *not* match — useful for filtering out noise.Example: grep
#!/bin/bash
printf "apple\nbanana\ncherry\navocado\n" > fruits.txt
echo "Lines containing 'a':"
grep "a" fruits.txt
echo "Lines starting with 'a':"
grep "^a" fruits.txtLogin to try C/C++/Java/PHP code in the editor
Related Topics
{# common_mistakes/chapter_summary/browser_support: on Hindi pages the
view already swaps in the hi_ translation fields (or blanks these
out if untranslated), so this renders correctly for both languages
without a lang_code check here. #}
Common Mistakes
- Forgetting quotes around the pattern, so the shell interprets special characters.
- Using
grepwith regex characters like.and expecting a plain string; use-F. - Checking
grepresults in anifwithout-q.
🔒
Chapter Quiz — Complete all 12 topics to unlock
0/12 topics done
Complete these topics first: