PASSWD(1)                  OpenBSD Reference Manual                  PASSWD(1)

NAME
     passwd - modify a user's password

SYNOPSIS
     passwd [-K | -l | -y] [user]

DESCRIPTION
     passwd changes the user's local, Kerberos, or YP password.  First, the
     user is prompted for their current password.  If the current password is
     correctly typed, a new password is requested.  The new password must be
     entered twice to avoid typing errors.

     The new password should be at least six characters long and not purely
     alphabetic.  Its total length must be less than _PASSWORD_LEN (currently
     128 characters).  A mixture of both lower and uppercase letters, numbers,
     and meta-characters is encouraged.

     The quality of the password can be enforced by specifying an external
     checking program via the ``passwordcheck'' variable in login.conf(5).

     The options are as follows:

     -K      Forces the change to affect the Kerberos 5 database, even if the
             user has a password in the local database.  Once the password has
             been verified, passwd communicates the new password information
             to the Kerberos authenticating host.

             The user argument specifies a principal and optional realm, for
             example ``user@DOMAIN.COM''.

     -l      Causes the password to be updated only in the local password
             file.  When changing only the local password, pwd_mkdb(8) is used
             to update the password databases.

     -y      Forces the YP password database entry to be changed, even if the
             user has an entry in the local database.  The rpc.yppasswdd(8)
             daemon should be running on the YP master server.

     This is the behavior if no flags are specified: if Kerberos is active
     then passwd will talk to the Kerberos server (even if the user has an en-
     try in the local database).  If the password is not in the local password
     database, then an attempt is made to use the YP database.

     The superuser is not required to provide a user's current password if on-
     ly the local password is modified.

     Which type of cipher is used to encrypt the password information depends
     on the configuration in login.conf(5).  It can be different for local
     (``localcipher'') and YP (``ypcipher'') passwords.  If none is specified,
     then blowfish with 6 rounds is used for local (``localcipher'') and old
     is used for YP (``ypcipher'') by default.

FILES
     /etc/login.conf     configuration options
     /etc/master.passwd  user database
     /etc/passwd         a 6th Edition-style password file
     /etc/passwd.XXXXXX  temporary copy of the password file
     /etc/ptmp           lock file for the passwd database

DIAGNOSTICS
     Attempting lock password file, please wait or press ^C to abort

     The password file is currently locked by another process; passwd will
     keep trying to lock the password file until it succeeds or you hit the
     interrupt character (control-C by default).  If passwd is interrupted
     while trying to gain the lock the password changed will be lost.

     If the process holding the lock was prematurely terminated the lock file
     may be stale and passwd will wait forever trying to lock the password
     file.  To determine whether a live process is actually holding the lock,
     the admin may run the following:

           $ fstat /etc/ptmp

     If no process is listed, it is safe to remove the /etc/ptmp file to clear
     the error.

SEE ALSO
     chpass(1), kinit(1), login(1), login.conf(5), passwd(5), pwd_mkdb(8),
     vipw(8)

     Robert Morris and Ken Thompson, UNIX password security.

HISTORY
     A passwd command appeared in Version 3 AT&T UNIX.

OpenBSD 4.7                      May 31, 2007                                2
