Check the UNIX group database for errors
Contributed by qmchenry 
September 4, 2003 
Tagged: UNIX
UNIX systems store user group information in the /etc/group file. Errors in this file can cause various problems.
To check the /etc/group file for errors, as superuser run:
grpck
If it returns no output, the command found no errors. Any errors it finds should be self-explanatory.