extract UID from /etc/passwd using RegEx

Question

I would like to extract UID from /etc/passwd file which looks like this-

www-data:x:33:33:www-data:/var/www:/bin/sh

The problem I'm facing is that even if I match first 33, the second 33 (GID) is also getting matched. How I match first occurrence only?

So far I've this- [\d]+

Can you limit your regex matcher to one match only? – alex Dec 29 '11 at 03:07 — alex, Dec 29 '11 at 03:07
What regex are you currently using? – wadesworld Dec 29 '11 at 03:10 — wadesworld, Dec 29 '11 at 03:10
updated with what I've right now – user837208 Dec 29 '11 at 03:13 — user837208, Dec 29 '11 at 03:13

holygeek · Answer 1 · 2011-12-29T03:17:28.897

0

That x in the second field used to contain the crypted password. Nowadays you can pretty much be sure that it is x for all entries so you can use the following:

$ grep x:33 /etc/passwd

See shadow password for details on that x.

You didn't tell us what you were trying to do actually so I'll take a guess that you might want to look at the man id man page.

If it's only uid that you're interested in then you can use cut:

$ cut -f 3 -d: /etc/passwd

edited Dec 29 '11 at 03:17

answered Dec 29 '11 at 03:11

holygeek

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I am trying to extract UID from /etc/passwd file – user837208 Dec 29 '11 at 03:14

score 0 · Accepted Answer · answered Dec 29 '11 at 03:14

0

You need to use a possessive-quantifier:

Try

[\d]+?

answered Dec 29 '11 at 03:14

wadesworld

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extract UID from /etc/passwd using RegEx

2 Answers2