PASSWD(5)                   BSD File Formats Manual                  PASSWD(5)

NAME
     passwd, master.passwd -- format of the password file

DESCRIPTION
     The /etc/passwd file is a legacy BSD 4.3 format file.  It is mostly
     unused, but is updated by some utility programs.  Its format is similar
     to the /etc/master.passwd file, except that it does not contain the
     class, change, and expire fields described below.

     The /etc/master.passwd file comprises newline separated records, one per
     user.  Each line contains 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     User's full name.

           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.

     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 the user's full name.  Note that Mac OS
     X differs from some other operating systems, where the gecos field may
     contain other comma-separcted information about the user.

     The home_dir field is the user's home directory.  This is the full 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.

INTERACTION WITH DIRECTORY SERVICES
     Processes generally find user records using one of the getpwent(3) family
     of functions.  On Mac OS X, these functions interact with the
     DirectoryService(8) daemon, which reads the /etc/master.passwd file as
     well as searching other directory information services to find user
     accounts.

FILES
     /etc/passwd
     /etc/master.passwd

SEE ALSO
     chpass(1), login(1), passwd(1), getpwent(3), netgroup(5),
     DirectoryService(8), pwd_mkdb(8), vipw(8)

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

BSD                              July 18, 1995                             BSD