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from: @(#)passwd.1 8.1 (Berkeley) 6/6/93
.Dd February 25, 2005 .Dt PASSWD 1 .Os .Sh NAME .Nm passwd .Nd modify a user's password .Sh SYNOPSIS .Nm .Op Ar user .Nm .Oo Fl d Ar files | Fl l Oc .Op Ar user .Nm .Oo Fl d Ar nis | Fl y Oc .Op Ar user .Nm .Oo Fl d Ar krb5 | Fl k Oc .Op Ar principal .Sh DESCRIPTION .Nm 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.
p The new password should be at least six characters long and not purely alphabetic. Its total length must be less than .Dv _PASSWORD_LEN (currently 128 characters). Numbers, upper case letters and meta characters are encouraged.
p All options may not be available on all systems. l -tag -width flag t Fl d Ar database This option specifies the password database that should be updated. The following databases are supported: l -tag -width files t files This specifies that the password change should be applied to the local password file. When changing only the local password, .Nm uses .Xr pwd_mkdb 8 to update the password databases. t nis This specifies that the password change should be applied to the NIS password database. The .Xr rpc.yppasswdd 8 daemon should be running on the master NIS server. t krb5 This specifies that the user's Kerberos 5 password should be changed. The host must be configured to use Kerberos. See .Xr krb5.conf 5 . .El t Fl l This is the equivalent of .Fl d Ar files . t Fl y This is the equivalent of .Fl d Ar nis . t Fl k This is the equivalent of .Fl d Ar krb5 . .El
p If a password database is not specified, .Nm will change the password database as determined by the Pluggable Authentication Module
q PAM library.
p The type of cipher used to encrypt the password depends on the configuration in .Xr passwd.conf 5 . It can be different for local and NIS passwords. .Sh FILES l -tag -width /etc/master.passwd -compact t Pa /etc/master.passwd The user database t Pa /etc/passwd A Version 7 format password file t Pa /etc/passwd.XXXXXX Temporary copy of the password file .El .Sh SEE ALSO .Xr chpass 1 , .Xr login 1 , .Xr pwhash 1 , .Xr passwd 5 , .Xr passwd.conf 5 , .Xr pam 8 , .Xr pwd_mkdb 8 , .Xr vipw 8 .Rs .%A Robert Morris .%A Ken Thompson .%T "UNIX password security" .Re .Sh HISTORY A .Nm command appeared in .At v6 .