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                                 07/24/2009                                                   GRPCK(8)