# grpck

## 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** _CHROOT_DIR_
               Apply changes in the _CHROOT_DIR_ directory and use the
               configuration files from the _CHROOT_DIR_ directory. Only
               absolute paths are supported.
    
           **-s** , **--sort**
               Sort entries in /etc/group and /etc/gshadow by GID.
    
           **-S** , **--silence-warnings**
               Suppress more controversial warnings, in particular warnings
               about inconsistency between group members listed in /etc/group
               and /etc/ghadow.
    
           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
    


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