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Trevor logs into his account on ssh://foobar.university.edu as one of the developers on the box, and he gets the message:

 id: cannot find name for group ID 131

Trevor then checks this out using

 vim /etc/group


Trevor discovers that there is no 131 anywhere in the /etc/group file.

Trevor then runs id ...

 > id trevor
 uid=4460(trevor) gid=131 groups=48(foobar),51(doobar),131

To discover his primary group apparently does not have a name attached to it.


  • What likely happened to cause this circumstance on the foobar.university.edu box ?
  • Suppose trevor wants to fix this (e.g., by just creating a "trevor" group that maps to GID 131) what is the best way to do this without potentially breaking anything else on the server ?
share|improve this question
Or maybe you have an incorrectaccess right on /etc/group file. – Pavel Patrin Apr 3 '15 at 13:32
up vote 10 down vote accepted

What likely happened is that the UID and GID are provided to the server via LDAP. If the /etc/group file doesn't contain the translation for the GID, then the server administrators likely just failed to update the group definitions. What can you do? Not much. The user id is controlled by the administrator. (Now if you happen to have ROOT privileges, you can add the group into /etc/group. You should also check to see if any other user accounts are using the same group, and if they are, name the group appropriately).

share|improve this answer
Thanks for the reply. Additional note: If you do have sufficient privileges; adding to group file can be done via groupadd --gid 131 foobargroup – dreftymac Nov 6 '12 at 1:54
@dreftymac Assuming that running id reports the same ID for uid, gid and groups, I guess it is safe to groupadd -gID username? – Boris Jul 9 at 7:46

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