passwd - modify a user's password
passwd [-l] [-y] [-K] [user]
passwd changes the user's local, Kerberos, or YP password.
user is prompted for their current password. If the current
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
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
checking program via the ``passwordcheck'' variable in login.conf(5).
The options are as follows:
-l Causes the password to be updated only in the local
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
daemon should be running on the YP master server.
-K Forces the change to affect the Kerberos 5 database,
even if the
user has a password in the local database. Once the
been verified, passwd communicates the new password
to the Kerberos authenticating host.
This is the behavior if no flags are specified: if Kerberos
then passwd will talk to the Kerberos server (even if the
user has an entry
in the local database). If the password is not in the
database, then an attempt is made to use the YP database.
The superuser is not required to provide a user's current
password if only
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
(``localcipher'') and YP (``ypcipher'') passwords. If none
then blowfish with 6 rounds is used for local (``localcipher'') and old
is used for YP (``ypcipher'') by default.
/etc/login.conf configuration options
/etc/master.passwd user database
/etc/passwd a Version 7 format password file
/etc/passwd.XXXXXX temporary copy of the password file
/etc/ptmp lock file for the passwd database
Attempting lock password file, please wait or press ^C to
The password file is currently locked by another process;
keep trying to lock the password file until it succeeds or
you hit the
interrupt character (control-C by default). If passwd is
while trying to gain the lock the password changed will be
If the process holding the lock was prematurely terminated
the lock file
may be stale and passwd will wait forever trying to lock the
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
chpass(1), kinit(1), login(1), login.conf(5), passwd(5),
Robert Morris and Ken Thompson, UNIX password security.
A passwd command appeared in Version 3 AT&T UNIX.
OpenBSD 3.6 July 24, 1991
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