coreutils: groups invocation

1 
1 20.4 ‘groups’: Print group names a user is in
1 =============================================
1 
1 ‘groups’ prints the names of the primary and any supplementary groups
1 for each given USERNAME, or the current process if no names are given.
1 If more than one name is given, the name of each user is printed before
1 the list of that user’s groups and the user name is separated from the
1 group list by a colon.  Synopsis:
1 
1      groups [USERNAME]...
1 
1    The group lists are equivalent to the output of the command ‘id -Gn’.
1 
11    The only options are ‘--help’ and ‘--version’.  ⇒Common
 options.
1 
1    Primary and supplementary groups for a process are normally inherited
1 from its parent and are usually unchanged since login.  This means that
1 if you change the group database after logging in, ‘groups’ will not
1 reflect your changes within your existing login session.  Running
1 ‘groups’ with a list of users causes the user and group database to be
1 consulted afresh, and so will give a different result.
1 
1    An exit status of zero indicates success, and a nonzero value
1 indicates failure.
1