]> pwck 8 System Management Commands pwck verify integrity of password files pwck -q -s passwd shadow pwck -q -r 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 (or the files in /etc/tcb, when USE_TCB is enabled) 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 options which apply to the pwck command are: -q Report errors only. The warnings which do not require any action from the user won't be displayed. -r Execute the pwck command in read-only mode. -s Sort entries in /etc/passwd and /etc/shadow by UID. This option has no effect when USE_TCB is enabled. By default, pwck operates on the files /etc/passwd and /etc/shadow (or the files in /etc/tcb). The user may select alternate files with the passwd and shadow parameters. Note that when USE_TCB is enabled, you cannot specify an alternative shadow file. In future releases, this paramater could be replaced by an alternate TCB directory. The following configuration variables in /etc/login.defs change the behavior of this tool: &PASS_MAX_DAYS; &PASS_MIN_DAYS; &PASS_WARN_AGE; &TCB_AUTH_GROUP; &TCB_SYMLINKS; &USE_TCB; /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 group5 , grpck8 , passwd5 , shadow5 , usermod8 .