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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)

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GRPCK(8)						    System Management Commands							  GRPCK(8)

NAME
grpck - verify integrity of group files SYNOPSIS
grpck [options] [group [ shadow ]] DESCRIPTION
The grpck command verifies the integrity of the groups information. It checks that all entries in /etc/group and /etc/gshadow have the proper format and contain valid data. The user is prompted to delete entries that are improperly formatted or which have other uncorrectable errors. Checks are made to verify that each entry has: o the correct number of fields o a unique and valid group name o a valid group identifier (/etc/group only) o a valid list of members and administrators o a corresponding entry in the /etc/gshadow file (respectively /etc/group for the gshadow checks) The checks for correct number of fields and unique group name are fatal. If an entry has the wrong number of fields, the user will be prompted to delete the entire line. If the user does not answer affirmatively, all further checks are bypassed. An entry with a duplicated group name is prompted for deletion, but the remaining checks will still be made. All other errors are warnings and the user is encouraged to run the groupmod command to correct the error. The commands which operate on the /etc/group and /etc/gshadow files are not able to alter corrupted or duplicated entries. grpck should be used in those circumstances to remove the offending entries. OPTIONS
The -r and -s options cannot be combined. The options which apply to the grpck command are: -h, --help Display help message and exit. -r, --read-only Execute the grpck command in read-only mode. This causes all questions regarding changes to be answered no without user intervention. -R, --root CHROOT_DIR Apply changes in the CHROOT_DIR directory and use the configuration files from the CHROOT_DIR directory. -s, --sort Sort entries in /etc/group and /etc/gshadow by GID. By default, grpck operates on /etc/group and /etc/gshadow. The user may select alternate files with the group and shadow parameters. 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/passwd User account information. EXIT VALUES
The grpck command exits with the following values: 0 success 1 invalid command syntax 2 one or more bad group entries 3 can't open group files 4 can't lock group files 5 can't update group files SEE ALSO
group(5), groupmod(8), gshadow(5), passwd(5), pwck(8), shadow(5). shadow-utils 4.1.5.1 05/25/2012 GRPCK(8)
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