Provided by: passwd_4.1.4.1-1ubuntu2_i386 bug

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 system authentication
       information. All entries in /etc/group and /etc/gshadow are checked to
       see that the entry has the proper format and valid data in each field.
       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:

       ·   the correct number of fields

       ·   a unique group name

       ·   a valid list of members and administrators

       The checks for correct number of fields and unique group name are
       fatal. If the 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 file are not able to alter
       corrupted or duplicated entries.  grpck should be used in those
       circumstances to remove the offending entry.

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.

SEE ALSO

       group(5), groupmod(8), gshadow(5) passwd(5), pwck(8), shadow(5).

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