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 their 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 a 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. Only absolute paths are supported.

SETUP

       The groupmems executable should be in mode 2710 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 2710 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 4.13                                  05/30/2024                                       GROUPMEMS(8)