# grpck(8) - man - phpMan

[GRPCK(8)](https://www.chedong.com/phpMan.php/man/GRPCK/8/markdown)                             System Management Commands                             [GRPCK(8)](https://www.chedong.com/phpMan.php/man/GRPCK/8/markdown)



## 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:

       •   the correct number of fields

       •   a unique and valid group name

       •   a valid group identifier (/etc/group only)

       •   a valid list of members and administrators

       •   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
           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)](https://www.chedong.com/phpMan.php/man/group/5/markdown), [**groupmod**(8)](https://www.chedong.com/phpMan.php/man/groupmod/8/markdown), [**gshadow**(5)](https://www.chedong.com/phpMan.php/man/gshadow/5/markdown), [**passwd**(5)](https://www.chedong.com/phpMan.php/man/passwd/5/markdown), [**pwck**(8)](https://www.chedong.com/phpMan.php/man/pwck/8/markdown), [**shadow**(5)](https://www.chedong.com/phpMan.php/man/shadow/5/markdown).



shadow-utils 4.8.1                           02/06/2024                                     [GRPCK(8)](https://www.chedong.com/phpMan.php/man/GRPCK/8/markdown)