chpass - add or change user database information
chpass [ -a list ] [ user ]
Chpass allows editing of the user database information associated with user or, by
default, the current user. The information is formatted and supplied to an editor for
changes. The vi editor will be used unless the environmental variable EDITOR selects 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 informa-
tion associated with the user.
Only the information that the user is allowed to change is displayed.
Possible display items are as follows:
Login: user's login name
Password: user's encrypted password
Uid: user's id
Gid: user's login group id
Change: password change time
Expire: account expiration time
Class: user's general classification
Home Directory: user's home directory
Shell: user's login shell
Full Name: user's real name
Location: user's normal location
Home Phone: user's home phone
Office Phone: user's office phone
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
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 upon login. Since this sys-
tem supports multiple groups (see groups(1)) this field currently has little special mean-
ing. This field may be filled in with either a number or a group name (see group(5)).
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.
The class field is currently unused. In the near future it will be a key to a termcap(5)
style database of user attributes.
The user's home directory is the full UNIX path name where the user will be placed on
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 must select an approved
shell from the list in /etc/shells.
The last four fields are for storing the user's full name, office location, and home and
work telephone numbers.
The super-user is also allowed to directly supply a user database entry, in the format
specified by passwd(5), as an argument to the -a option. This argument must be a colon
(``:'') separated list of all the user database fields, although they may be empty.
Once the information has been verified, chpass uses mkpasswd(8) to update the user data-
base. This is run in the background, and, at very large sites could take several minutes.
Until this update is completed, the password file is unavailable for other updates and the
new information will not be available to programs.
/etc/master.passwd The user database /etc/shells The list of approved
login(1), finger(1), getusershell(3), passwd(5), mkpasswd(8), vipw(8)
Robert Morris and Ken Thompson, UNIX password security
User information should (and eventually will) be stored elsewhere.
4th Berkeley Distribution March 12, 1989 CHPASS(1)