Hello m.roth at 5-cent.us, On Wed, 15 Aug 2012 11:47:21 -0400 m.roth at 5-cent.us wrote: > 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.... I found that regexp particularly simple :-D. Not here to troll, but simple or complicated, I think it's only about a bit of knowledge (understanding), a learning curve. Personally I don't feel comfortable w/ awk expressions/language. Not saying that one if better than the other - I would rather think that knowing both is way better. Don't be afraid with regular expressions, there's nothing really complex about most of them! Regards, -- wwp -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 198 bytes Desc: not available URL: <http://lists.centos.org/pipermail/centos/attachments/20120816/8d1f873a/attachment-0005.sig>