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@(#)chpass.1 5.7 (Berkeley) 06/01/89
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 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 this system 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 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 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 .
The last four fields are for storing the user's full name, office location, and home and work telephone numbers.
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.
-s The -s option attempts to change the user's shell to newsh .
Once the information has been verified, chpass uses mkpasswd (8) to update the user database. 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.
Robert Morris and Ken Thompson, UNIX password security