centos man page for groupmems

GROUPMEMS(8)						    System Management Commands						      GROUPMEMS(8)

NAME
       groupmems - administer members of a user's primary group

SYNOPSIS
       groupmems -a user_name | -d user_name | [-g group_name] | -l | -p

DESCRIPTION
       The groupmems command allows a user to administer his/her own group membership list without the requirement of superuser privileges. The
       groupmems utility is for systems that configure its users to be in their own name sake primary group (i.e., guest / guest).

       Only the superuser, as administrator, can use groupmems to alter the memberships of other groups.

OPTIONS
       The options which apply to the groupmems command are:

       -a, --add user_name
	   Add an user to the group membership list.

	   If the /etc/gshadow file exist, and the group has no entry in the /etc/gshadow file, a new entry will be created.

       -d, --delete user_name
	   Delete a user from the group membership list.

	   If the /etc/gshadow file exist, the user will be removed from the list of members and administrators of the group.

	   If the /etc/gshadow file exist, and the group has no entry in the /etc/gshadow file, a new entry will be created.

       -g, --group group_name
	   The superuser can specify which group membership list to modify.

       -h, --help
	   Display help message and exit.

       -l, --list
	   List the group membership list.

       -p, --purge
	   Purge all users from the group membership list.

	   If the /etc/gshadow file exist, and the group has no entry in the /etc/gshadow file, a new entry will be created.

       -R, --root CHROOT_DIR
	   Apply changes in the CHROOT_DIR directory and use the configuration files from the CHROOT_DIR directory.

SETUP
       The groupmems executable should be in mode 2770 as user root and in group groups. The system administrator can add users to group groups to
       allow or disallow them using the groupmems utility to manage their own group membership list.

		$ groupadd -r groups
		$ chmod 2770 groupmems
		$ chown root.groups groupmems
		$ groupmems -g groups -a gk4

CONFIGURATION
       The following configuration variables in /etc/login.defs change the behavior of this tool:

       MAX_MEMBERS_PER_GROUP (number)
	   Maximum members per group entry. When the maximum is reached, a new group entry (line) is started in /etc/group (with the same name,
	   same password, and same GID).

	   The default value is 0, meaning that there are no limits in the number of members in a group.

	   This feature (split group) permits to limit the length of lines in the group file. This is useful to make sure that lines for NIS
	   groups are not larger than 1024 characters.

	   If you need to enforce such limit, you can use 25.

	   Note: split groups may not be supported by all tools (even in the Shadow toolsuite). You should not use this variable unless you really
	   need it.

FILES
       /etc/group
	   Group account information.

       /etc/gshadow
	   secure group account information

SEE ALSO
       chfn(1), chsh(1), passwd(1), groupadd(8), groupdel(8), useradd(8), userdel(8), usermod(8).

shadow-utils 4.1.5.1						    05/25/2012							      GROUPMEMS(8)