PASSWD(5)                   BSD Programmer's Manual                  PASSWD(5)

NAME
     passwd - format of the password file

DESCRIPTION
     The passwd files are files consisting of newline separated records, one
     per user, containing ten colon (``:'') separated fields.  These fields
     are as follows:

           name      User's login name.

           password  User's encrypted password.

           uid       User's id.

           gid       User's login group id.

           class     User's general classification (unused).

           change    Password change time.

           expire    Account expiration time.

           gecos     General information about the user.

           home_dir  User's home directory.

           shell     User's login shell.

     The name field is the login used to access the computer account, and the
     uid field is the number associated with it.  They should both be unique
     across the system (and often across a group of systems) since they con-
     trol 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 login name must never begin with a hyphen (``-''); also, it is
     strongly suggested that neither upper-case characters or dots (``.'') be
     part of the name, as this tends to confuse mailers.  No field may contain
     a colon (``:'') as this has been used historically to separate the fields
     in the user database.

     The password field is the encrypted form of the password.  If the
     password field is empty, no password will be required to gain access to
     the machine.  This is almost invariably a mistake.  Because these files
     contain the encrypted user passwords, they should not be readable by any-
     one without appropriate privileges.

     The group field is the group that the user will be placed in upon login.
     Since this system supports multiple groups (see groups(1))  this field
     currently has little special meaning.

     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 change field is the number in seconds, GMT, from the epoch, until the
     password for the account must be changed.  This field may be left empty
     to turn off the password aging feature.

     The expire field is the number in seconds, GMT, from the epoch, until the
     account expires.  This field may be left empty to turn off the account
     aging feature.

     The gecos field normally contains comma (``,'') separated subfields as
     follows:

           name      user's full name
           office         user's office number
           wphone         user's work phone number
           hphone         user's home phone number

     This information is used by the finger(1) program.

     The user's home directory is the full UNIX path name where the user will
     be placed on login.

     The shell field is the command interpreter the user prefers.  If there is
     nothing in the shell field, the Bourne shell (/bin/sh) is assumed.

SEE ALSO
     chpass(1),  login(1),  passwd(1),  getpwent(3),  mkpasswd(8),  vipw(8)
     adduser(8)

BUGS
     User information should (and eventually will) be stored elsewhere.

HISTORY
     A passwd file format appeared in Version 6 AT&T UNIX.

BSDI BSD/386                    March 27, 1993                               2