CHPASS(1) BSD General Commands Manual CHPASS(1)NAME
chpass, chfn, chsh, ypchpass, ypchfn, ypchsh — add or change user data‐
chpass [-a list] [-p encpass] [-e expiretime] [-s newshell] [user]
chpass [-oly] [-a list] [-p encpass] [-e expiretime] [-s newshell]
[-d domain] [-h host] [user]
The chpass utility allows editing of the user database information asso‐
ciated with user or, by default, the current user.
The chfn, chsh, ypchpass, ypchfn and ypchsh utilities behave identically
to chpass. (There is only one program.)
The information is formatted and supplied to an editor for changes.
Only the information that the user is allowed to change is displayed.
The options are as follows:
-a The super-user is allowed to directly supply a user database
entry, in the format specified by passwd(5), as an argument.
This argument must be a colon (“:”) separated list of all the
user database fields, although they may be empty.
-p The super-user is allowed to directly supply an encrypted pass‐
word field, in the format used by crypt(3), as an argument.
Change the account expire time. This option is used to set the
expire time from a script as if it was done in the interactive
Attempt to change the user's shell to newshell.
Possible display items are as follows:
Login: user's login name
Password: user's encrypted password
Uid: user's login
Gid: user's login group
Class: user's general classification
Change: password change time
Expire: account expiration time
Full Name: user's real name
Office Location: user's office location (1)
Office Phone: user's office phone (1)
Home Phone: user's home phone (1)
Other Information: any locally defined parameters for user (1)
Home Directory: user's home directory
Shell: user's login shell
NOTE(1) - In the actual master.passwd file, these fields
are comma-delimited fields embedded in the
The login field is the user name used to access the computer account.
The password field contains the encrypted form of the user's password.
The uid field is the number associated with the login field. Both of
these fields should be unique across the system (and often across a group
of systems) as they control file access.
While it is possible to have multiple entries with identical login names
and/or identical user id's, it is usually a mistake to do so. Routines
that manipulate these files will often return only one of the multiple
entries, and that one by random selection.
The group field is the group that the user will be placed in at login.
Since BSD supports multiple groups (see groups(1)) this field currently
has little special meaning. This field may be filled in with either a
number or a group name (see group(5)).
The class field references class descriptions in /etc/login.conf and is
typically used to initialize the user's system resource limits when they
The change field is the date by which the password must be changed.
The expire field is the date on which the account expires.
Both the change and expire fields should be entered in the form “month
day year” where month is the month name (the first three characters are
sufficient), day is the day of the month, and year is the year.
Five fields are available for storing the user's full name, office
location, work and home telephone numbers and finally other information
which is a single comma delimited string to represent any additional
gecos fields (typically used for site specific user information). Note
that finger(1) will display the office location and office phone together
under the heading Office:.
The user's home directory is the full UNIX path name where the user will
be placed at login.
The shell field is the command interpreter the user prefers. If the
shell field is empty, the Bourne shell, /bin/sh, is assumed. When alter‐
ing a login shell, and not the super-user, the user may not change from a
non-standard shell or to a non-standard shell. Non-standard is defined
as a shell not found in /etc/shells.
Once the information has been verified, chpass uses pwd_mkdb(8) to update
the user database.
The vi(1) editor will be used unless the environment variable EDITOR is
set to an alternate editor. When the editor terminates, the information
is re-read and used to update the user database itself. Only the user,
or the super-user, may edit the information associated with the user.
See pwd_mkdb(8) for an explanation of the impact of setting the
PW_SCAN_BIG_IDS environment variable.
The chpass utility can also be used in conjunction with NIS, however some
restrictions apply. Currently, chpass can only make changes to the NIS
passwd maps through rpc.yppasswdd(8), which normally only permits changes
to a user's password, shell and GECOS fields. Except when invoked by the
super-user on the NIS master server, chpass (and, similarly, passwd(1))
cannot use the rpc.yppasswdd(8) server to change other user information
or add new records to the NIS passwd maps. Furthermore, rpc.yppasswdd(8)
requires password authentication before it will make any changes. The
only user allowed to submit changes without supplying a password is the
super-user on the NIS master server; all other users, including those
with root privileges on NIS clients (and NIS slave servers) must enter a
password. (The super-user on the NIS master is allowed to bypass these
restrictions largely for convenience: a user with root access to the NIS
master server already has the privileges required to make updates to the
NIS maps, but editing the map source files by hand can be cumbersome.
Note: these exceptions only apply when the NIS master server is a FreeBSD
Consequently, except where noted, the following restrictions apply when
chpass is used with NIS:
1. Only the shell and GECOS information may be changed. All
other fields are restricted, even when chpass is invoked by
the super-user. While support for changing other fields could
be added, this would lead to compatibility problems with other
NIS-capable systems. Even though the super-user may supply
data for other fields while editing an entry, the extra infor‐
mation (other than the password -- see below) will be silently
Exception: the super-user on the NIS master server is permit‐
ted to change any field.
2. Password authentication is required. The chpass utility will
prompt for the user's NIS password before effecting any
changes. If the password is invalid, all changes will be dis‐
Exception: the super-user on the NIS master server is allowed
to submit changes without supplying a password. (The super-
user may choose to turn off this feature using the -o flag,
3. Adding new records to the local password database is
discouraged. The chpass utility will allow the administrator
to add new records to the local password database while NIS is
enabled, but this can lead to some confusion since the new
records are appended to the end of the master password file,
usually after the special NIS '+' entries. The administrator
should use vipw(8) to modify the local password file when NIS
The super-user on the NIS master server is permitted to add
new records to the NIS password maps, provided the
rpc.yppasswdd(8) server has been started with the -a flag to
permitted additions (it refuses them by default). The chpass
utility tries to update the local password database by
default; to update the NIS maps instead, invoke chpass with
the -y flag.
4. Password changes are not permitted. Users should use
passwd(1) or yppasswd(1) to change their NIS passwords. The
super-user is allowed to specify a new password (even though
the “Password:” field does not show up in the editor template,
the super-user may add it back by hand), but even the super-
user must supply the user's original password otherwise
rpc.yppasswdd(8) will refuse to update the NIS maps.
Exception: the super-user on the NIS master server is permit‐
ted to change a user's NIS password with chpass.
There are also a few extra option flags that are available when chpass is
compiled with NIS support:
-l Force chpass to modify the local copy of a user's password infor‐
mation in the event that a user exists in both the local and NIS
-y Opposite effect of -l. This flag is largely redundant since
chpass operates on NIS entries by default if NIS is enabled.
Specify a particular NIS domain. The chpass utility uses the
system domain name by default, as set by the domainname(1) util‐
ity. The -d option can be used to override a default, or to
specify a domain when the system domain name is not set.
Specify the name or address of an NIS server to query. Normally,
chpass will communicate with the NIS master host specified in the
master.passwd or passwd maps. On hosts that have not been con‐
figured as NIS clients, there is no way for the program to deter‐
mine this information unless the user provides the hostname of a
server. Note that the specified hostname need not be that of the
NIS master server; the name of any server, master or slave, in a
given NIS domain will do.
When using the -d option, the hostname defaults to “localhost”.
The -h option can be used in conjunction with the -d option, in
which case the user-specified hostname will override the default.
-o Force the use of RPC-based updates when communicating with
rpc.yppasswdd(8) (“old-mode”). When invoked by the super-user on
the NIS master server, chpass allows unrestricted changes to the
NIS passwd maps using dedicated, non-RPC-based mechanism (in this
case, a UNIX domain socket). The -o flag can be used to force
chpass to use the standard update mechanism instead. This option
is provided mainly for testing purposes.
/etc/master.passwd the user database
/etc/passwd a Version 7 format password file
/etc/chpass.XXXXXX temporary copy of the password file
/etc/shells the list of approved shells
SEE ALSOfinger(1), login(1), passwd(1), getusershell(3), login.conf(5),
passwd(5), pw(8), pwd_mkdb(8), vipw(8)
and Robert Morris and Ken Thompson, UNIX Password security.
The chpass utility appeared in 4.3BSD-Reno.
User information should (and eventually will) be stored elsewhere.
BSD December 30, 1993 BSD