grpck(8) [linux man page]

GRPCK(8)						    System Management Commands							  GRPCK(8)

NAME

       grpck - verify integrity of group files

SYNOPSIS

       grpck [-r] [group [ shadow ]]

       grpck [-s] [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 options which apply to the grpck command are:

       -r
	   Execute the grpck command in read-only mode. This causes all questions regarding changes to be answered no without user intervention.

       -s
	   Sort entries in /etc/group and /etc/gshadow by GID.

       By default, grpck operates on /etc/groupand /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).

System Management Commands					    06/24/2011								  GRPCK(8)

Check Out this Related 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)

Linux and UNIX Man Pages

grpck(8) [linux man page]

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