pwck - verify integrity of password files
pwck [-sr] [passwd shadow]
pwck verifies the integrity of the system authentication information.
All entries in the /etc/passwd and /etc/shadow are checked to see that
the entry has the proper format and valid data in each field. The user
is prompted to delete entries that are improperly formatted or which
have other incorrectable errors.
Checks are made to verify that each entry has
- the correct number of fields
- a unique user name
- a valid user and group identifier
- a valid primary group
- a valid home directory
- a valid login shell
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.
By default, pwck operates on the files /etc/passwd and /etc/shadow.
The user may select alternate files with the passwd and shadow parame-
ters. Additionally, the user may execute the command in read-only mode
by specifying the -r flag. This causes all questions regarding changes
to be answered no without user intervention. pwck can also sort
entries in /etc/passwd and /etc/shadow by UID. To run it in sort mode
pass it -s flag. No checks are performed then, it just sorts.
/etc/passwd - user account information
/etc/shadow - encrypted password information
/etc/group - group information
group(5), passwd(5), shadow(5), usermod(8)
The pwck command exits with the following values:
1 Syntax Error
2 One or more bad password entries
3 Cannot open password files
4 Cannot lock password files
5 Cannot update password files
Julianne Frances Haugh (firstname.lastname@example.org)