passwd
From NetBSD Wiki
The passwd(1) allows a user to change his password.
The easiest use of the command is simply
$ passwd Old Password: **** New Password: **** Retype New Password: ****
It does some basic checking and lets you know if the password is too easy to break. (if you're absolutely certain, you can type it in again and it will still accept it)
Root can change anyone's password by supplying a username on the commandline:
# passwd yoda New Password: **** Retype New Password: ****
The reason the old password is asked for a normal user is so nobody can trick you when you're not looking. It is implicitly assumed that when you're root you know what you're doing and won't turn your back on the machine while a root prompt is open.
