GRPCK linux command manual

GRPCK(1)                                                           GRPCK(1)

       grpck - verify integrity of group files

       grpck [-r] [group shadow]

       grpck verifies the integrity of the system authentication information.
       All entries in the /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 incorrectable 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.

       By  default,  grpck operates on the files /etc/group and /etc/gshadow.
       The user may select alternate files with the group and shadow  parame-
       ters.   Additionally,  the  user  may execute the command in read-only
       mode by specifying the -r flag.  This causes all  questions  regarding
       changes  to  be answered no without user intervention.  grpck can also
       sort entries in /etc/group and /etc/gshadow by GID. To run it in  sort
       mode pass it -s flag. No checks are performed then, it just sorts.

       /etc/group - group account information
       /etc/gshadow - encrypted passwords and group administrator information
       /etc/passwd - user information

       group(5), passwd(5), shadow(5), groupmod(8)

       The grpck command exits with the following values:

       0    Success

       1    Syntax Error

       2    One or more bad group entries

       3    Cannot open group files

       4    Cannot lock group files

       5    Cannot update group files

       Julianne Frances Haugh (