Provided by: passwd_4.1.1-1ubuntu1_i386 bug


       passwd - change user password


       passwd [options] [LOGIN]


       The passwd command changes passwords for user accounts. A normal user
       may only change the password for his/her own account, while the
       superuser may change the password for any account.  passwd also changes
       account information, such as the full name of the user, the user´s
       login shell, or his/her password expiry date and interval.

   Password Changes
       The user is first prompted for his/her old password, if one is present.
       This password is then encrypted and compared against the stored
       password. The user has only one chance to enter the correct password.
       The superuser is permitted to bypass this step so that forgotten
       passwords may be changed.

       After the password has been entered, password aging information is
       checked to see if the user is permitted to change the password at this
       time. If not, passwd refuses to change the password and exits.

       The user is then prompted twice for a replacement password. The second
       entry is compared against the first and both are required to match in
       order for the password to be changed.

       Then, the password is tested for complexity. As a general guideline,
       passwords should consist of 6 to 8 characters including one or more
       characters from each of the following sets:

       ·   lower case alphabetics

       ·   digits 0 thru 9

       ·   punctuation marks

       Care must be taken not to include the system default erase or kill
       characters.  passwd will reject any password which is not suitably

   Hints for user passwords
       The security of a password depends upon the strength of the encryption
       algorithm and the size of the key space. The UNIX System encryption
       method is based on the NBS DES algorithm and is very secure. The size
       of the key space depends upon the randomness of the password which is

       Compromises in password security normally result from careless password
       selection or handling. For this reason, you should not select a
       password which appears in a dictionary or which must be written down.
       The password should also not be a proper name, your license number,
       birth date, or street address. Any of these may be used as guesses to
       violate system security.

       Your password must be easily remembered so that you will not be forced
       to write it on a piece of paper.


       The options which apply to the passwd command are:

       -a, --all
           This option can be used only with -S and causes show status for all

       -d, --delete
           Delete a user´s password (make it empty). This is a quick way to
           disable a password for an account. It will set the named account

       -e, --expire
           Immediately expire an account´s password. This in effect can force
           a user to change his/her password at the user´s next login.

       -h, --help
           Display help message and exit.

       -i, --inactive INACTIVE
           This option is used to disable an account after the password has
           been expired for a number of days. After a user account has had an
           expired password for INACTIVE days, the user may no longer sign on
           to the account.

       -k, --keep-tokens
           Indicate password change should be performed only for expired
           authentication tokens (passwords). The user wishes to keep their
           non-expired tokens as before.

       -l, --lock
           Lock the named account. This option disables an account by changing
           the password to a value which matches no possible encrypted value,
           and by setting the account expiry field to 1.

       -m, --mindays MIN_DAYS
           Set the minimum number of days between password changes to
           MIN_DAYS. A value of zero for this field indicates that the user
           may change his/her password at any time.

       -q, --quiet
           Quiet mode.

       -r, --repository REPOSITORY
           change password in REPOSITORY repository

       -S, --status
           Display account status information. The status information consists
           of 7 fields. The first field is the user´s login name. The second
           field indicates if the user account is locked (L), has no password
           (NP), or has a usable password (P). The third field gives the date
           of the last password change. The next four fields are the minimum
           age, maximum age, warning period, and inactivity period for the
           password. These ages are expressed in days.

       -u, --unlock
           Unlock the named account. This option re-enables an account by
           changing the password back to its previous value (to value before
           using -l option), and by resetting the account expiry field.

       -w, --warndays WARN_DAYS
           Set the number of days of warning before a password change is
           required. The WARN_DAYS option is the number of days prior to the
           password expiring that a user will be warned that his/her password
           is about to expire.

       -x, --maxdays MAX_DAYS
           Set the maximum number of days a password remains valid. After
           MAX_DAYS, the password is required to be changed.


       Not all options may be supported. Password complexity checking may vary
       from site to site. The user is urged to select a password as complex as
       he or she feels comfortable with. Users may not be able to change their
       password on a system if NIS is enabled and they are not logged into the
       NIS server.


           User account information.

           Secure user account information.


       The passwd command exits with the following values:


           permission denied

           invalid combination of options

           unexpected failure, nothing done

           unexpected failure, passwd file missing

           passwd file busy, try again

           invalid argument to option


       group(5), passwd(5), shadow(5).