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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | CONFIGURATION | FILES | EXIT VALUES | SEE ALSO | COLOPHON |
PWCK(8) System Management Commands PWCK(8)
pwck - verify integrity of password files
pwck [options] [passwd [ shadow ]]
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.
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.
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.
/etc/group
Group account information.
/etc/passwd
User account information.
/etc/shadow
Secure user account information.
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
group(5), grpck(8), passwd(5), shadow(5), usermod(8).
This page is part of the shadow-utils (utilities for managing
accounts and shadow password files) project. Information about the
project can be found at ⟨http://pkg-shadow.alioth.debian.org/⟩. If
you have a bug report for this manual page, see
⟨http://pkg-shadow.alioth.debian.org/getinvolved.php⟩. This page was
obtained from the project's upstream Git repository
⟨git://anonscm.debian.org/git/pkg-shadow/shadow.git⟩ on 2017-07-05.
If you discover any rendering problems in this HTML version of the
page, or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the information
in this COLOPHON (which is not part of the original manual page),
send a mail to man-pages@man7.org
shadow-utils 4.4 07/05/2017 PWCK(8)
Pages that refer to this page: passwd(5@@shadow-utils), shadow(5), grpck(8), pwconv(8)