04.3 - grep

grep is the ginsu knife of Unix! It slices, dices, and more!

grep is a tool to look through a stream (being a file, output from a program, or network traffic!) for a string.

grep {-v | -i } String2SearchFor file_to_search

The options I listed are

-v - all but the matching lines are liked (an opposite grep)

-i - case insenstive search

grep uses regular express syntax to specify what to find. Some common regular extension syntax

^ - the begining of the line

$ - the end of the line

[ ] - match any one of the characters listed

Example grep in log files

grep -i "^Jul 25 1[56]:" /var/log/kern.log

This will get lines out of /var/log/kern.log from July 25 from 15-16 hours.