groupmems(8) — Linux manual page


GROUPMEMS(8)             System Management Commands             GROUPMEMS(8)

NAME         top

       groupmems - administer members of a user's primary group

SYNOPSIS         top

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

DESCRIPTION         top

       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         top

       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.

SETUP         top

       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


       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         top

           Group account information.

           secure group account information

SEE ALSO         top

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

COLOPHON         top

       This page is part of the shadow-utils (utilities for managing
       accounts and shadow password files) project.  Information about the
       project can be found at ⟨⟩.  If
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       from the project's upstream Git repository
       ⟨⟩ on 2020-07-14.  (At that
       time, the date of the most recent commit that was found in the repos‐
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shadow-utils 4.6                 07/14/2020                     GROUPMEMS(8)