Mastering grep: Essential Syntax, Options, and Real-World Examples

grep (Global Regular Expression Print) is a powerful Linux utility for searching text using regular expressions and printing matching lines. It is available to all users and is a fundamental tool for command‑line text processing.

Basic syntax : grep [options] pattern [file...] Common options : -c: output only the count of matching lines. -i: ignore case distinctions. -h: suppress file name output when searching multiple files. -l: list only the names of files containing matches. -n: show line numbers of matches. -s: suppress error messages for nonexistent or unreadable files. -v: invert match, showing lines that do not match. --color=auto: highlight matched text.

Practical examples :

Find lines containing "png": grep -n 'png' linuxmi.py Find lines not containing "png": grep -vn 'png' linuxmi.py Match strings where "na" is not preceded by "v": grep -n '[^v]na' linuxmi.py Match strings where "na" is not preceded by any lowercase letter: grep -n '[^a-z]na' linuxmi.py Find lines starting with "ba": grep -n '^ba' linuxmi.py Find lines not starting with a letter: grep -n '^[^a-zA-Z]' linuxmi.py Find lines ending with a period: grep -n '\.$' linuxmi.py Match any two characters between "l" and "k": grep -n 'l..k' linuxmi.py Find lines containing consecutive "e" characters: grep -n 'eee*' linuxmi.py Find lines starting with "l", ending with "e", and containing at least one "x" in between: grep -n 'lxx*e' linuxmi.py Find lines starting with "l" and ending with "k", with any characters (or none) in between: grep -n 'l.*k' linuxmi.py Match exactly two consecutive "e" characters using a quantifier: grep -n 'e\{2\}' linuxmi.py Note: Characters like "." and "*" have special meanings in regular expressions and must be escaped (e.g., "\\.") when you need to match them literally.

Original article: https://urlify.cn/zaYrei