V10/man/man1/passwd.1

.TH PASSWD 1
.CT 1 comm_term sa_mortals secur
.SH NAME
passwd \(mi change login password
.SH SYNOPSIS
.B passwd
[
.B -an
]
[
.I name
]
.SH DESCRIPTION
This command changes a password
associated with the user
.IR name
(your own name by default).
.PP
The program prompts for the old password and then for the new one.
The caller must supply both.
The new password must be typed twice, to forestall mistakes.
.PP
New passwords must be at least four characters long if they use
a sufficiently rich alphabet and at least six characters long
if monocase.
These rules are relaxed if you are insistent enough.
.PP
Only the owner of the name or the super-user may change a password;
the owner must prove he knows the old password.
.PP
If the
.B -a
option is given,
.I passwd
prompts for new values of certain fields of the
password file entry.
.PP
The super-user may use the
.B -n
option to install new users.
The prompts are self-explanatory,
and most of the defaults obvious.
A null response to the
.L UID:
prompt
assigns a numeric userid one greater than the
largest one previously in
.FR /etc/passwd .
A null response to
.L Directory:
assigns a home directory in
.FR /usr .
If the first character of the response to this
prompt is an asterisk, the remaining characters
are taken as the name of the new user's home
directory, and a symbolic link to this directory
is placed in
.FR /usr .
.PP
If
.F /etc/stdprofile
exists, each new user's home directory starts with a file name
.FR .profile ,
which is a copy of
.F /etc/stdprofile
with
.B \eN
replaced by the user's name, and
.B \eD
replaced by the name of the home directory.
.SH FILES
.F /etc/passwd
.br
.F /etc/stdprofile
.SH "SEE ALSO"
.IR crypt (3)
.IR passwd (5)
.br
Robert Morris and Ken Thompson,
`UNIX password security,'
.I AT&T Bell Laboratories Technical Journal
63 (1984) 1649-1672
.SH BUGS
The password file information should be kept in a different data structure
allowing indexed access.