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