PWCK(8) 系统管理命令 PWCK(8)

pwck - 检查密码文件的完整性

pwck [选项] [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.


•有效的登录 shell

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



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:


Allow names that do not conform to standards.

-h, --help


-q, --quiet


-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)

一个密码可以使用的最大天数。如果密码比这旧,将会强迫更改密码。如果不指定,就假定为 -1,这会禁用这个限制。

PASS_MIN_DAYS (number)

两次更改密码时间的最小间隔。将会拒绝任何早于此的更改密码的尝试。如果不指定,假定为 -1,将会禁用这个限制。

PASS_WARN_AGE (number)

密码过期之前给出警告的天数。0 表示只有只在过期的当天警告,负值表示不警告。如果没有指定,不会给警告。






The pwck command exits with the following values:




invalid command syntax


one or more bad password entries


can't open password files


can't lock password files


can't update password files


can't sort password files

group(5), grpck(8), passwd(5), shadow(5), usermod(8).
2020-01-23 shadow-utils 4.8.1