[CentOS] Extract lines from text file

Wed Aug 15 14:33:18 UTC 2012
wwp <subscript at free.fr>

Hello Tony,


On Wed, 15 Aug 2012 15:22:10 +0100 Tony Molloy <tony.molloy at ul.ie> wrote:

> 
> Hi,
> 
> 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?


Regards,

-- 
wwp
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