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 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.
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 4.8.1 02/07/2020 GROUPMEMS(8)