[CentOS] Extract lines from text file

Wed Aug 15 15:47:21 UTC 2012
m.roth at 5-cent.us <m.roth at 5-cent.us>

wwp wrote:
> On Wed, 15 Aug 2012 15:22:10 +0100 Tony Molloy <tony.molloy at ul.ie> wrote:
>>
>> I'm looking for a command to extract lines from a large text file, a
>> password file. A typical user has a username made from a letter
>> followed by their id-number.
>>
>> m9718508:pw:9301:840: Lynch  :/home/pgstud/m9718508:/bin/bash
>>
>> So for instance if I need to extract lines where;
>> the 1st field, the username begins with an m
>> and the 4th field, the group contains exactly 850
>>
>> cat passwdfile | grep ^m | grep 850 > output
>>
>> is close but fails if the value 850 appears outside the 4th field. In
>> the above example which should be ignored 850 appears in the username
>> and home directory and is therefore extracted.
>
> Something like `grep -E '^m.+:.*:.*:850:'` maybe?

Complicated.

awk '{ if ($1 ~ /^m/ && $4 == "850" ) { print $0;}}' /etc/passwd

    mark "awk! awk!*"

* No, I'm still not a seagull....