| PWCK(8) | System Management Commands | PWCK(8) |
.SH "NAME" pwck - verify the integrity of password files
.SH "SYNOPSIS"
.HP 120u
pwck
[options]
[PASSWORDFILE [ SHADOWFILE ]]
.SH "DESCRIPTION"
.PP 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.
.PP Checks are made to verify that each entry has:
.RE
.RE
.RE
.RE
.RE
.RE
.PP Checks for shadowed password information are enabled when the second file
parameter SHADOWFILE is specified or when /etc/shadow exists on the
system.
.PP These checks are the following:
.RE
.RE
.RE
.RE
.RE
.PP 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 warnings and the user is encouraged to run the
usermod command to correct the error.
.PP 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.
.SH "OPTIONS"
.PP The -r and -s options cannot be combined.
.PP The options which apply to the pwck command are:
.PP --badname
Allow names that do not conform to standards.
.RE
.PP -h, --help
Display help message and exit.
.RE
.PP -q, --quiet
Report errors only. The warnings which do not require any action from the user won't be displayed.
.RE
.PP -r, --read-only
Execute the pwck command in read-only mode.
.RE
.PP -R, --root CHROOT_DIR
Apply changes in the CHROOT_DIR directory and use the configuration files from the CHROOT_DIR directory. Only absolute paths are supported. No SELINUX support.
.RE
.PP -s, --sort
Sort entries in /etc/passwd and /etc/shadow by UID.
.RE
.PP By default, pwck operates on the files /etc/passwd and
/etc/shadow. The user may select alternate files with the passwd and
shadow parameters.
.SH "CONFIGURATION"
.PP The following configuration variables in /etc/login.defs change the
behavior of this tool:
NONEXISTENT (string)
If a system account intentionally does not have a home directory that exists,
this string can be provided in the /etc/passwd entry for the account to
indicate this. The result is that pwck will not emit a spurious warning for
this account.
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_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 value of -1 means no
warning is given. If not specified, no warning will be provided.
.SH "FILES"
.PP /etc/group
Group account information.
.RE
.PP /etc/passwd
User account information.
.RE
.PP /etc/shadow
Secure user account information.
.RE
.SH "EXIT VALUES"
.PP The pwck command exits with the following values:
.PP 0
success
.RE .PP 1
invalid command syntax
.RE .PP 2
one or more bad password entries
.RE .PP 3
can't open password files
.RE .PP 4
can't lock password files
.RE .PP 5
can't update password files
.RE .PP 6
can't sort password files
.RE
.SH "SEE ALSO"
.PP group(5), grpck(8), passwd(5), shadow(5),
usermod(8).
| 10/09/2026 | shadow-utils 4.20.3 |