pwck(8)

NAME

   pwck - verify integrity of password files

SYNOPSIS

   pwck [options] [passwd [ shadow ]]

DESCRIPTION

   The pwck command verifies the integrity of the users and authentication
   information. It checks that all entries in /etc/passwd and /etc/shadow
   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 user name

   *   a valid user and group identifier

   *   a valid primary group

   *   a valid home directory

   *   a valid login shell

   shadow checks are enabled when a second file parameter is specified or
   when /etc/shadow exists on the system.

   These checks are the following:

   *   every passwd entry has a matching shadow entry, and every shadow
       entry has a matching passwd entry

   *   passwords are specified in the shadowed file

   *   shadow entries have the correct number of fields

   *   shadow entries are unique in shadow

   *   the last password changes are not in the future

   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.

OPTIONS

   The -r and -s options cannot be combined.

   The options which apply to the pwck command are:

   -h, --help
       Display help message and exit.

   -q, --quiet
       Report errors only. The warnings which do not require any action
       from the user won't be displayed.

   -r, --read-only
       Execute the pwck command in read-only mode.

   -R, --root CHROOT_DIR
       Apply changes in the CHROOT_DIR directory and use the configuration
       files from the CHROOT_DIR directory.

   -s, --sort
       Sort entries in /etc/passwd and /etc/shadow by UID.

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

CONFIGURATION

   The following configuration variables in /etc/login.defs change the
   behavior of this tool:

   PASS_MAX_DAYS (number)
       The maximum number of days a password may be used. If the password
       is older than this, a password change will be forced. If not
       specified, -1 will be assumed (which disables the restriction).

   PASS_MIN_DAYS (number)
       The minimum number of days allowed between password changes. Any
       password changes attempted sooner than this will be rejected. If
       not specified, -1 will be assumed (which disables the restriction).

   PASS_WARN_AGE (number)
       The number of days warning given before a password expires. A zero
       means warning is given only upon the day of expiration, a negative
       value means no warning is given. If not specified, no warning will
       be provided.

FILES

   /etc/group
       Group account information.

   /etc/passwd
       User account information.

   /etc/shadow
       Secure user account information.

EXIT VALUES

   The pwck command exits with the following values:

   0
       success

   1
       invalid command syntax

   2
       one or more bad password entries

   3
       can't open password files

   4
       can't lock password files

   5
       can't update password files

   6
       can't sort password files

SEE ALSO

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

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