grep Unix OS Command/r&d22112011

grep (is beautiful)

•  Search through stdin for things

•  Sends to stdout lines matched lines

            $ grep tacos

                this   line   has   tacos
                this   line    has   tacos
                this   line   dosen't
                more  tacos
                more  tacos 

•  You can do the same in awk with

              $ awk '/tacos/{print $0}'

             Ex1.  $ grep B2  

             Ex2. $ grep A4

             Ex3.$ grep C3

• -B prints lines before match
•  -A prints lines after each match
•  -C prints the lines before and after
•  -i case insenstive search
•  -v prints lines with no match
•  -c prints just number of matches
•  --color highlights matches

•  Fancy regular expressions: -E
•  Example: Match IP range from 172.22.21.1 to 172.22.21.35:

Example:

$ grep E   '172\.22\.21\.([19]|( 1[09]| 2[09]| 3[05])) ' hosts.txt


xargs (to the rescue)
Example: run cvs update in all subfolders:

find . type  d | xargs i t sh c \ 'cd {};cvs update'