On Wednesday 15 August 2012 15:36:09 Marcelo Beckmann wrote: > Em 15-08-2012 11:22, Tony Molloy escreveu: > > 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. > > > > Any ideas. > > ]$ cat testcentoslist > m9718508:pw:9301:840: Lynch :/home/pgstud/m9718508:/bin/bash > m9718308:pw:9301:850: Lynch :/home/pgstud/m9718508:/bin/bash > m9718208:pw:9301:840: Lynch :/home/pgstud/m9718508:/bin/bash > m9718508:pw:9301:840: Lynch :/home/pgstud/m9718908:/bin/bash > > ]$ cat testcentoslist | egrep ^m.*:.*:.*:850: > m9718308:pw:9301:850: Lynch :/home/pgstud/m9718508:/bin/bash > Exactly what I needed. I'll just drop the cat as a later poster pointed out. Thanks to all who replied. Tony