PWCK(1)                                                                PWCK(1)

       pwck - verify integrity of password files

       pwck [-sr] [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 further 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  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.   pwck can also sort
       entries in /etc/passwd and /etc/shadow by UID. To run it in  sort  mode
       pass it -s flag. No checks are performed then, it just sorts.

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

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

       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 (