PASSWD(1) PASSWD(1)
NAME
passwd - change login password
SYNOPSIS
passwd [ -an ] [ name ]
DESCRIPTION
This command changes a password associated with the user
name (your own name by default).
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.
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 insis-
tent enough.
Only the owner of the name or the super-user may change a
password; the owner must prove he knows the old password.
If the -a option is given, passwd prompts for new values of
certain fields of the password file entry.
The super-user may use the -n option to install new users.
The prompts are self-explanatory, and most of the defaults
obvious. A null response to the `UID:' prompt assigns a
numeric userid one greater than the largest one previously
in A null response to `Directory:' assigns a home directory
in 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
If exists, each new user's home directory starts with a file
name which is a copy of with \N replaced by the user's name,
and \D replaced by the name of the home directory.
FILES
SEE ALSO
crypt(3) passwd(5)
Robert Morris and Ken Thompson, `UNIX password security,'
AT&T Bell Laboratories Technical Journal 63 (1984) 1649-1672
BUGS
The password file information should be kept in a different
data structure allowing indexed access.