PASSWD(1) General Commands Manual PASSWD(1)
passwd, chfn, chsh - change local or NIS password information
passwd [ -l | -y ] [ -afs ] [ -d [ username ] ] [ -e username ]
[ -F filename ] [ -n numdays username ]
[ -x numdays username ] [ username ]
chfn [ -l | -y ] [ -f ] [ -F filename ] [ username ]
chsh [ -l | -y ] [ -s ] [ -F filename ] [ username ]
passwd changes (or installs) a password, login shell (-s option), or
full name (-f option) associated with the user username (your own by
default). chsh is equivalent to passwd with the -s option, and chfn is
equivalent to passwd with the -f option.
Use `passwd -y' or yppasswd(1) to change your password in the Network
Information Service (NIS). This will not affect your local password,
or your password on any remote machines on which you have accounts.
passwd calls yppasswd automatically if you do not have an entry in the
local passwd file, and the -l option is not specified.
When changing a password, passwd prompts for the old password and then
for the new one. You must supply both, and the new password must be
typed twice to forestall mistakes.
If password aging is enabled, the first time an ordinary user enters
the new password passwd checks to see if the old password has "aged"
sufficiently. Password "aging" is the amount of time (usually a cer-
tain number of days) that must elapse between password changes. If
"aging" is insufficient the new password is rejected and passwd termi-
New passwords should be at least five characters long, if they combine
upper-case and lower-case letters, or at least six characters long if
in monocase. Users that persist in entering shorter passwords are com-
promising their own security. The number of significant characters in a
password is eight, although longer passwords will be accepted.
Only the owner of the name or the super-user may change a password; the
owner must prove he knows the old password. The super-user can change
any password and is not forced to comply with password aging require-
When changing a login shell, passwd displays the current login shell
and then prompts for the new one. The new login shell must be one of
the approved shells listed in /etc/shells unless you are the super-
user. If /etc/shells does not exist, the only shells that may be spec-
ified are /bin/sh and /bin/csh.
The super-user may change anyone's login shell; normal users may only
change their own login shell.
When changing a full name, passwd displays the current full name,
enclosed between brackets, and prompts for a new full name. If you
type a RETURN, the full name is not changed. If the full name is to be
made blank, you must type the word "none".
The super-user may change anyone's full name; normal users may only
change their own.
-a Display the name and aging information for all users. Can only
be invoked by the super-user.
-f Change the full name.
-l Change the local password, login shell, or full name. If user-
name exists in the local passwd file, this is the default.
-s Change the login shell.
-y Change passwd, login shell, or full name in the NIS database.
Display the name and aging information for the caller or the
user specified if the invoker has the right privileges.
Expire the password for the user name specified. Can only be
invoked by the super-user.
Treat filename as the password file.
-n numdays username
Set the maturity time of the password for username. Passwords
that have not "aged" enough cannot be changed. Can only be set
by the super-user.
-x numdays username
Set the expiration time of the password for username. Can only
be set by the super-user.
/etc/passwd file containing all of this information
/etc/shells list of approved shells
finger(1), login(1), yppasswd(1), crypt(3), passwd(5)
Password algorithms do not work with 8-bit characters. This maintains
consistency with login file naming rules, which do not allow 8-bit
characters in login names. See login(1) for explanations about why
login is not 8-bit clean.
The Network Information Service (NIS) was formerly known as Sun Yellow
Pages (YP). The functionality of the two remains the same; only the
name has changed.
12 June 1988 PASSWD(1)