add or change user database information
utility allows editing of the user
database information associated with user
by default, the current user.
utilities behave identically to
. (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:
- The super-user is allowed to directly supply a user database entry, in the
format specified by
as an argument. This argument must be a colon (“:”)
separated list of all the user database fields, although they may be
- The super-user is allowed to directly supply an encrypted password field,
in the format used by
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 editor.
- Attempt to change the user's shell to
Possible display items are as follows:
- user's login name
- user's encrypted password
- user's login
- user's login group
- user's general classification
- password change time
- 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
- user's login shell
- NOTE(1) -
- In the actual master.passwd file, these fields are comma-delimited fields
embedded in the FullName field.
field is the user name used to access
the computer account.
field contains the encrypted form
of the user's password.
field is the number associated with the
field. Both of these fields should be
unique across the system (and often across a group of systems) as they control
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.
field is the group that the user will
be placed in at login. Since BSD
this field currently has little special meaning. This field may be filled in
with either a number or a group name (see
field references class descriptions
and is typically used to
initialize the user's system resource limits when they login.
field is the date by which the
password must be changed.
field is the date on which the
Both the change
fields should be entered in the form
“month day year” where month
the month name (the first three characters are sufficient),
is the day of the month, and
is the year.
Five fields are available for storing the user's full
, office location
numbers and finally other
which is a single comma delimited string to represent any
additional gecos fields (typically used for site specific user information).
will display the office location and office phone together under the heading
The user's home directory
is the full
path name where the user will be placed at login.
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,
to update the user database.
editor will be used unless the environment variable
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.
for an explanation of the impact of setting the
utility can also be used in
conjunction with NIS, however some restrictions apply. Currently,
can only make changes to the NIS
passwd maps through
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,
cannot use the
server to change other user information or add new records to the NIS passwd
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
Consequently, except where noted, the following restrictions apply when
is used with NIS:
- 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
Exception: the super-user on the NIS master server is permitted to change
- 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
- Adding new records to the local password database
is discouraged. The
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
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
server has been started with the
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
- Password changes are not permitted. Users
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
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
There are also a few extra option flags that are available when
is compiled with NIS support:
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 databases.
- Opposite effect of
-l. This flag is
largely redundant since
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
-d option can be used to
override a default, or to specify a domain when the system domain name is
- Specify the name or address of an NIS server to query. Normally,
chpass will communicate with the NIS
master host specified in the
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
-d option, in which case the
user-specified hostname will override the default.
- Force the use of RPC-based updates when communicating with
(“old-mode”). When invoked by the super-user on the NIS
unrestricted changes to the NIS passwd maps using dedicated, non-RPC-based
mechanism (in this case, a UNIX domain socket).
-o flag can be used to force
chpass to use the standard update
mechanism instead. This option is provided mainly for testing
- the user database
- a Version 7 format password file
- temporary copy of the password file
- the list of approved shells
Robert Morris and
Ken Thompson, UNIX Password
utility appeared in
User information should (and eventually will) be stored elsewhere.