grep

Find the lines with some text in files

What it does

grep prints the lines that contain the text you look for. What to find comes first, then where: grep error app.log. If the text has spaces or special characters, put it in quotes.

-i ignores case, -n adds line numbers, -r searches every file in a folder and its subfolders, and -v does the opposite, keeping the lines without a match. Without a file, grep reads what comes in through a pipe.

Syntax

grep <text> <file>
grep -rn <text> <folder>
grep -i <text> <file>

Examples

• Find every TODO in the src folder, with line numbers

  grep -rn "TODO" src

  same as: grep -nr "TODO" src, grep -rn TODO src, grep -nr TODO src

  • grep — search text
  • -r — in every file of the folder
  • -n — with line numbers
  • "TODO" src — what to find and where

• Find lines in app.log with the word error in any case

  grep -i error app.log

  same as: grep -i "error" app.log, grep --ignore-case error app.log

  • grep — search text
  • -i — ignore case: Error, ERROR
  • error app.log — what to find and where

Related commands

• find — Find files and folders by name, type and more
• cat — Print a file to the terminal
• | — The pipe. Pass the output of one command to the input of another

Practise · All commands