pwck

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:

Checks for shadowed password information are enabled when the second file parameter SHADOWFILE is specified or when /etc/shadow exists on the system.

These checks are the following:

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.

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

NONEXISTENT (string)

PASS_MAX_DAYS (number)

PASS_MIN_DAYS (number)

PASS_WARN_AGE (number)

/etc/group

/etc/passwd

/etc/shadow

The pwck command exits with the following values:

0

1

2

3

4

5

6