NAME

       Net::NIS - Interface to Sun's Network Information Service

SYNOPSIS

         use Net::NIS;
         tie %hash, 'Net::NIS', $mapname [, $domainname];
         $value = $hash{$key};

       or

         ($status, $value) = Net::NIS::yp_match
                                 (Net::NIS::yp_get_default_domain(),
                                 $mapname, $key);

DESCRIPTION

       The Net::NIS interface comes in three parts:

       1. raw
           The first part is the raw implementation of the NIS API.

       2. OO
           The second is the object interface, described in Net::NIS::Table.

       3. Tie
           The third is a new 'Tied' interface, allowing simple access to NIS maps using Perl
           hashes.

       This document describes the NIS API implementation and the 'Tied' mechanism.

   Tied Implementation
       NIS maps are simple key/value pairs, perfectly suited for Perl hashes.  Net::NIS allows
       any given NIS map to be treated as a hash (read-only).  Usage is:

           tie %hash, 'Net::NIS', $mapname [, $domainname];

       $mapname must be specified, and be a valid map in the given domain.  If the file
       /var/yp/nicknames exists, it is used to obtain a list of acceptable shortcut names, such
       as "aliases" for "mail.aliases".  Otherwise, a hardcoded set of the "usual suspects" is
       consulted.

       If $domainname is not given, the "yp_get_default_domain" function is used to determine the
       current NIS domain.  This is usually the same as will be displayed by the "domainname"
       command.

       If Net::NIS cannot tie to a given map, it returns "undef", with an appropriate error value
       in the variable $yperr.  See "ERRORS".

       To look up an entry in a YP map, simply use the entry name as a key in the tied hash.
       Net::NIS returns a string if the key exists in the map, or "undef" if it is not found.
       For any errors other than YPERR_KEY, Net::NIS raises a fatal exception through "croak".

       Example

         tie %alias, 'Net::NIS', 'mail.aliases'
           or die "Cannot tie to mail.aliases YP map: $yperr\n";
         print "postmaster is ", $alias{postmaster} || "<unknown>", "\n";

       As a special case, the magic map __YPMASTER can be used as an equivalent to 'ypwhich -m':

         tie %ypmaster, 'Net::NIS', '__YPMASTER' or die ...;
         printf "ypmaster(passwd) = %s\n", $ypmaster{'passwd.byname'};

         print  $_, "\n"    for sort keys %ypmaster;   # Only works on Linux!

       Note that keys() only works on Linux, because Linux includes a helpful yp_maplist()
       function.  On Linux, you can get a list of existing YP maps.  On other OSes, you can't --
       but given the name of an existing map, $ypmaster{$map} will work as expected.

   NIS API Implementation
       The NIS package implements all functions described in the ypclnt(3N) manual page.

       The following commands have been implemented:

       yp_bind($domain)
            Bind the process to a NIS server for the domain $domain.  This function is rarely
            needed.  See yp_bind(3N).

       yp_unbind($domain)
            Unbind the process from the specified $domain.  This function is also rarely
            required.  See yp_unbind(3N).

       $domain = yp_get_default_domain()
            Return the host's local domain.  (The same as the domainname program).  See
            yp_get_default_domain(3N).

       ($status, $value) = yp_match($domain, $map, $key)
            Return the $value for the given $key in the $map for the domain $domain.  The $key
            must be an exact match for an item in the map (i.e.  yp_match does no partial
            matching.  The $value is only valid if $status is equal to YPERR_SUCCESS.

            If called in scalar context, yp_match returns only $value, and it is up to the user
            to check $yperr.

       ($status, $key, $value) = yp_first($domain, $map)
            Return the first key-value pair from $map in $domain.  As the NIS maps are stored in
            a DBM table, the order of the returned values is not obvious.

       ($status, $key, $value) = yp_next($domain, $map, $key)
            Return the next key-value pair from $map in $domain.  The $key must be provided from
            the previous yp_first or yp_next.  The yp_first/yp_next method is not recommended, as
            under some circumstances, entries can be skipped or returned twice.  yp_all is a
            better interface to use.

       ($status, \%values) = yp_all($domain, $map)
            The yp_all call returns an entire map in the %values associative array.

       ($status, $order) = yp_order($domain, $map)
            This function returns the order number for $domain.  Whatever that is.  It mustn't be
            very important, since it's not implemented on NIS+ servers running in "YP-
            compatibility mode".  I put it in for completeness.

       ($status, $name) = yp_master($domain, $map)
            Returns the machine name of the master server for a map.

       $error = yperr_string($status) [DEPRECATED, use $yperr]
            Returns a string representation of the error code passed in $status.

       $status = ypprot_err($code) [DEPRECATED]
            Translates a NIS name service protocol error code to a ypclnt layer error code.  Only
            used for the C version of yp_all, and it is only implemented here for completeness.

EXPORT

       The magic variable $yperr is exported by default (see "ERRORS").

   Exportable constants
       The following error status constants can be imported individually, or by using the ':all'
       symbol:

           YPERR_SUCCESS       There is no error
           YPERR_BADARGS       Args to function are bad
           YPERR_RPC           RPC failure
           YPERR_DOMAIN        Can't bind to a server with this domain
           YPERR_MAP           No such map in server's domain
           YPERR_KEY           No such key in map
           YPERR_YPERR         Internal yp server or client error
           YPERR_RESRC         Local resource allocation failure
           YPERR_NOMORE        No more records in map database
           YPERR_PMAP          Can't communicate with portmapper
           YPERR_YPBIND        Can't communicate with ypbind
           YPERR_YPSERV        Can't communicate with ypserv
           YPERR_NODOM         Local domain name not set
           YPERR_BADDB         yp data base is bad
           YPERR_VERS          YP version mismatch
           YPERR_ACCESS        Access violation
           YPERR_BUSY          Database is busy

ERRORS

       Instead of having 'tie' succeed and the first access fail, TIEHASH() (the function
       executed when performing a tie) performs some sanity checks: it ensures the validity of
       the domain and map names.  On failure, 'tie' returns "undef", with an appropriate error
       value in $yperr :

           tie %myhash, 'Net::NIS', 'foo-bar'
             or die "Unable to access foo-bar map: $yperr\n"

       Note that the $yperr variable is magic, like Perl's $!.  If accessed in a string context,
       it returns a human-friendly string obtained from the "yperr_string" library function.  In
       a numeric context, $yperr returns the numeric status code returned from the last YP
       function.  This can be compared against the error constants above, if you so desire.

   Other Errors
           Your vendor has not defined Net::NIS macro YPERR_xxxx

       This indicates that one of the standard YPERR_xxx constants is not defined in your host's
       <rpcsct/ypclnt.h> file.  You might see this during make test on an old system, perhaps.

           Unable to find 'KEY' in 'MAP'.  Reason: ...

       If an attempt to access a tied variable fails for any reason other than 'no such key in
       map', FETCH() raises this fatal exception.  It probably indicates that YP has gone down,
       or there is some other fatal error.  This can be caught with eval{}, but I'm not sure what
       you can do about it...

AUTHOR

       Copyright (c) 1995, 2002 Rik Harris (rik.harris@fulcrum.com.au), 2002-2014 Ed Santiago.
       All rights reserved.  This program is free software; you can redistribute it and/or modify
       it under the same terms as Perl itself.

       Net::NIS is currently maintained by Ed Santiago <esm@cpan.org>.

       The Network Information Service (NIS) was formerly known as Sun Yellow Pages (YP). The
       functionality of the two remains the same; only the name has changed.  The name Yellow
       Pages is a registered trademark in the United Kingdom of British Telecommunications plc,
       and may not be used without permission.