Comments on: Hack 17. Grep Command Examples

By: Dhanesh

Dhanesh — Tue, 14 Jun 2011 04:09:56 +0000

i have a file which contains different combination of numbers
eg :
1 2 3 4 5 6
1 2 3 4
1 2 3 4 5 6 7 8 9

i want to seach 1 2 3 4 5 6, and want to get all the results which contain these 6 numbers and also 1 2 3 4 should show in my results

murali — Wed, 10 Feb 2010 00:32:55 +0000

hi ,
what is d dirrerence between
a. grep “John Doe” my-file > /dev/null 2>&1
b. grep “John Doe” my-file 2>&1 > /dev/null

Jahman — Fri, 15 Jan 2010 21:08:50 +0000

Hi,

Another tip , grep is very slow on UTF-8. Use “LANG=C grep …” to increase speed.

$ echo $LANG
en_US.UTF-8
$ time grep ‘^….’ /usr/share/dict/words >/dev/null
real 2m16.795s
user 2m10.536s
sys 0m0.087s

$ export LANG=C
$ time grep ‘^….’ /usr/share/dict/words >/dev/null
real 0m0.031s
user 0m0.028s
sys 0m0.003s