PASSWD(1)			 User Commands			     PASSWD(1)



NAME
       passwd - change user password

SYNOPSIS
       passwd [options] [LOGIN]

DESCRIPTION
       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:

       o   lower case alphabetics

       o   digits 0 thru 9

       o   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
       complex.

   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
       selected.

       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.

OPTIONS
       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
	   users.

       -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
	   passwordless.

       -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.

CAVEATS
       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.

FILES
       /etc/passwd
	   User account information.

       /etc/shadow
	   Secure user account information.

EXIT VALUES
       The passwd command exits with the following values:

       0
	   success

       1
	   permission denied

       2
	   invalid combination of options

       3
	   unexpected failure, nothing done

       4
	   unexpected failure, passwd file missing

       5
	   passwd file busy, try again

       6
	   invalid argument to option

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



User Commands			  12/08/2008			     PASSWD(1)