Search a string in files with grep, egrep, fgrep, pgrep, and locale — Cheat Sheet Linux

grep

grep <OPTIONS> <PATTERN> <FILENAME> displays the lines of a file corresponding to a specified pattern.

The arguments are:

• -c (or --count): displays a count of matching lines for each input file,
• -C <NUMBER> (or --context): displays context lines between continuous groups of matches,
• -E <PATTERN> (or --extended-regexp): uses the pattern as an extended regular expression,