GROUPMEMS(8)              (02/07/2020)               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 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.

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              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 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

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

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