PWCK(1)                                                   PWCK(1)

       pwck - verify integrity of password files

       pwck [-r] [passwd shadow]

       pwck  verifies  the integrity of the system authentication
       information.   All  entries   in   the   /etc/passwd   and
       /etc/shadow  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 user name
            - a valid user and group identifier
            - a valid primary group
            - a valid home directory
            - a valid login shell

       The checks for correct number of fields  and  unique  user
       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 fur-
       ther checks are bypassed.  An entry with a duplicated user
       name  is  prompted  for deletion, but the remaining checks
       will still be made.  All other errors are warning and  the
       user  is  encouraged to run the usermod command to correct
       the error.

       The commands which operate on the /etc/passwd file are not
       able  to  alter  corrupted  or  duplicated  entries.  pwck
       should be  used  in  those  circumstances  to  remove  the
       offending entry.

       By  default,  pwck  operates  on the files /etc/passwd and
       /etc/shadow.  The user may select alternate files with the
       passwd  and shadow parameters.  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.

       /etc/passwd - user account information
       /etc/shadow - encrypted password information
       /etc/group - group information

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

       The pwck command exits with the following values:

       0    Success

       1    Syntax Error

       2    One or more bad password entries

       3    Cannot open password files

       4    Cannot lock password files

       5    Cannot update password files

       Julianne Frances Haugh (