getgrgid GID
This function does the same thing as getgrgid(3): it looks up a group file entry by group number. The return value in list context is:
($name, $passwd, $gid, $members)
where
$members
contains a space-separated list of the login names of the members of the group.
If you want to do this repeatedly, consider caching the data in a hash
(associative array) using
getgrent.
In scalar context, getgrgid returns only the group name.