groupmems(8) [centos man page]
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)
Check Out this Related Man Page
GROUPMOD(8) System Management Commands GROUPMOD(8) NAME
groupmod - modify a group definition on the system SYNOPSIS
groupmod [options] GROUP DESCRIPTION
The groupmod command modifies the definition of the specified GROUP by modifying the appropriate entry in the group database. OPTIONS
The options which apply to the groupmod command are: -g, --gid GID The group ID of the given GROUP will be changed to GID. The value of GID must be a non-negative decimal integer. This value must be unique, unless the -o option is used. Users who use the group as primary group will be updated to keep the group as their primary group. Any files that have the old group ID and must continue to belong to GROUP, must have their group ID changed manually. No checks will be performed with regard to the GID_MIN, GID_MAX, SYS_GID_MIN, or SYS_GID_MAX from /etc/login.defs. -h, --help Display help message and exit. -n, --new-name NEW_GROUP The name of the group will be changed from GROUP to NEW_GROUP name. -o, --non-unique When used with the -g option, allow to change the group GID to a non-unique value. -p, --password PASSWORD The encrypted password, as returned by crypt(3). Note: This option is not recommended because the password (or encrypted password) will be visible by users listing the processes. You should make sure the password respects the system's password policy. -R, --root CHROOT_DIR Apply changes in the CHROOT_DIR directory and use the configuration files from the CHROOT_DIR directory. 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. /etc/login.defs Shadow password suite configuration. /etc/passwd User account information. EXIT VALUES
The groupmod command exits with the following values: 0 success 2 invalid command syntax 3 invalid argument to option 4 specified group doesn't exist 6 specified group doesn't exist 9 group name already in use 10 can't update group file SEE ALSO
chfn(1), chsh(1), passwd(1), gpasswd(8), groupadd(8), groupdel(8), login.defs(5), useradd(8), userdel(8), usermod(8). shadow-utils 4.1.5.1 05/25/2012 GROUPMOD(8)