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


NAME

     passwd, master.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.  If this is set to ``-1'' then
     the user will be prompted to change their password at the next login.


     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.

     If either of the change or expire fields are set, the system will remind
     the user of the impending change or expiry if they login within the 14
     days before the event.

     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.


YP SUPPORT

     If YP is active, the passwd file also supports standard YP exclusions and
     inclusions, based on user names and netgroups.

     Lines beginning with a ``-'' (minus sign) are entries marked as being ex-
     cluded from any following inclusions, which are marked with a ``+'' (plus
     sign).

     If the second character of the line is a ``@'' (at sign), the operation
     involves the user fields of all entries in the netgroup specified by the
     remaining characters of the name field.  Otherwise, the remainder of the
     name field is assumed to be a specific user name.

     The ``+'' token may also be alone in the name field, which causes all
     users from the passwd.byname and passwd.byuid YP maps to be included.

     If the entry contains non-empty uid or gid fields, the specified numbers
     will override the information retrieved from the YP maps. As well, if the
     gecos, dir or shell entries contain text, it will override the informa-
     tion included via YP.  On some systems, the passwd field may also be
     overridden.


SEE ALSO

     chpass(1),  login(1),  passwd(1),  getpwent(3),  netgroup(5),
     adduser(8),  pwd_mkdb(8),  vipw(8),  yp(8)

     Managing NFS and NIS (O'Reilly & Associates)


BUGS

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

     Placing YP exclusions in the file after any inclusions will have unex-
     pected results.


COMPATIBILITY

     The password file format has changed since 4.3BSD.  The following awk
     script can be used to convert your old-style password file into a new
     style password file.  The additional fields ``class'', ``change'' and
     ``expire'' are added, but are turned off by default.  Class is currently
     not implemented, but change and expire are; to set them, use the current
     day in seconds from the epoch + whatever number of seconds of offset you
     want.

           BEGIN { FS = ":"}
           { print $1 ":" $2 ":" $3 ":" $4 "::0:0:" $5 ":" $6 ":" $7 }


HISTORY

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

     YP passwd file format first appeared in SunOS.

4.4BSD                          August 16, 1997                              3