43

How to get the group ID GID giving the group name.

The output would be for example:

Group adm with GID=4

4 Answers 4

58

Use the getent command for processing groups and user information, instead of manually reading /etc/passwd, /etc/groups etc. The system itself uses /etc/nsswitch.conf to decide where it gets its information from, and settings in the files may be overridden by other sources. getent obeys this configuration. getent prints data, no matter the source, in the same format as the files, so you can then parse the output the same way you would parse /etc/passwd:

getent group sudo | awk -F: '{printf "Group %s with GID=%d\n", $1, $3}'

Note that, for a username, this much more easier. Use id:

$ id -u lightdm
105
1
  • Ok, awk is shorter than perl =)
    – A.B.
    Jun 23, 2015 at 16:05
39

This can be simply done with cut:

$ cut -d: -f3 < <(getent group sudo)
27

getent group sudo will get the line regarding sudo group from /etc/group file :

$ getent group sudo
sudo:x:27:foobar

Then we can just take the third field delimited by :.

If you want the output string accordingly, use command substitution within echo:

$ echo "Group sudo with GID="$(cut -d: -f3 < <(getent group sudo))""
Group sudo with GID=27
6
  • % echo "Group cdrom with GID="$(cut -d: -f3 < <(getent group sudo))"" Group cdrom with GID=27, please a little more generic =)
    – A.B.
    Jun 23, 2015 at 16:07
  • 3
    Why the process substitution? What's wrong with GID="$(getent group cdrom | cut -d: -f3)"?
    – kos
    Jun 23, 2015 at 16:24
  • @kos I don't like running things in subshells unless is a must.....
    – heemayl
    Jun 23, 2015 at 17:08
  • @A.B. Edited...
    – heemayl
    Jun 23, 2015 at 17:37
  • 1
    Note, that this is Bash specific. Same result can be achieved with: getent group root | cut --delimiter ':' --fields 3 (or use short args). Seems like this case does not really require process substitution. Feb 16 at 17:29
3

A hack for the needed: (still maybe there is much better answer)

awk -F\: '{print "Group " $1 " with GID=" $3}' /etc/group | grep "group-name"

Simpler version(Thanks to @A.B):

awk -F\: '/sudo/ {print "Group " $1 " with GID=" $3}' /etc/group 

Example:

$ awk -F\: '{print "Group " $1 " with GID=" $3}' /etc/group | grep sudo 
Group sudo with GID=27
2
  • 1
    Try this: awk -F\: '/sudo/ {print "Group " $1 " with GID=" $3}' /etc/group
    – A.B.
    Jun 23, 2015 at 15:51
  • See UUOC
    – kos
    Jun 23, 2015 at 16:30
0

Using perl one-liner:

% perl -ne '@elements=(split /:/); printf "Group %s with GID=%s\n",$elements[0],$elements[2]' <<< $(getent group sudo)
Group sudo with GID=27

or shorter (and better)

% perl -F/:/ -ane 'printf "Group %s with GID=%s\n",$F[0],$F[2]' <<< $(getent group sudo)
Group sudo with GID=27
1
  • 2
    Pretty sure perl can do the splitting for you, I think the -F or -l option does that.
    – muru
    Jun 23, 2015 at 16:06

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