PASSWD(1) BSD General Commands Manual PASSWD(1)
passwd -- modify a user's password
passwd [-d files | -l] [user]
passwd [-d nis | -y] [user]
passwd [-d krb5 | -k] [principal]
passwd changes the user's 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 (cur-
rently 128 characters). Numbers, upper case letters and meta characters are encouraged.
All options may not be available on all systems.
This option specifies the password database that should be updated. The following databases are supported:
files This specifies that the password change should be applied to the local password file. When changing only the local password,
passwd uses pwd_mkdb(8) to update the password databases.
nis This specifies that the password change should be applied to the NIS password database. The rpc.yppasswdd(8) daemon should be
running on the master NIS server.
krb5 This specifies that the user's Kerberos 5 password should be changed. The host must be configured to use Kerberos. See
-l This is the equivalent of -d files.
-y This is the equivalent of -d nis.
-k This is the equivalent of -d krb5.
If a password database is not specified, passwd will change the password database as determined by the Pluggable Authentication Module (PAM)
The type of cipher used to encrypt the password depends on the configuration in passwd.conf(5). It can be different for local and NIS pass-
/etc/master.passwd The user database
/etc/passwd A Version 7 format password file
/etc/passwd.XXXXXX Temporary copy of the password file
chpass(1), login(1), pwhash(1), passwd(5), passwd.conf(5), pam(8), pwd_mkdb(8), vipw(8)
Robert Morris and Ken Thompson, UNIX password security.
A passwd command appeared in Version 6 AT&T UNIX.
February 25, 2005 BSD