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Grep - Basic usage

Assuming a file exists with the following contents:

boot
book
booze
machine
boots
bungie
bark
aardvark
broken$tuff
robots

Simple Search

grep "boo" filename

returns:

boot
book
booze
boots

NOTE: grep prints out every line that contains the word boo.

grep -n "boo" filename

returns:

1:boot
2:book
3:booze
5:boots

NOTE: Using the -n option prints includes line numbers.

grep -vn "boo" filename

returns:

4:machine
6:bungie
7:bark
8:aaradvark
9:robots

NOTE: Using the -v option prints the inverse of the search string.

This is the items not found.

grep -c "boo" filename

returns:

NOTE: grep prints out 4 as there are 4 occurrences of the word boo.

grep -l "boo" *

NOTE: The -l option prints only the filenames of files in the query that have lines that match the search string.

This is useful if you are searching through multiple files for the same string.