CHPASS(1) BSD General Commands Manual CHPASS(1)
chpass, chfn, chsh, ypchpass, ypchfn, ypchsh -- add or change user database information
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 associated 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 argu-
ment 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 password 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 edi-
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 FullName field.
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. Rou-
tines that manipulate these files will often return only one of the multiple entries, and that one by random selection.
The gid 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
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
altering 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 informa-
tion 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
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 system).
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 information (other than
the password -- see below) will be silently discarded.
Exception: the super-user on the NIS master server is permitted 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 discarded.
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, described below.)
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 is running.
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 permitted 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 information 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) utility.
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 configured as NIS clients, there is no way for the program to determine
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 pro-
vided 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
finger(1), login(1), passwd(1), getusershell(3), login.conf(5), passwd(5), pw(8), pwd_mkdb(8), vipw(8)
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.
December 30, 1993 BSD