NAME

       Errno - System errno constants

SYNOPSIS

           use Errno qw(EINTR EIO :POSIX);

DESCRIPTION

       "Errno" defines and conditionally exports all the error constants defined in your system
       errno.h include file. It has a single export tag, ":POSIX", which will export all POSIX
       defined error numbers.

       On Windows, "Errno" also defines and conditionally exports all the Winsock error constants
       defined in your system WinError.h include file. These are included in a second export tag,
       ":WINSOCK".

       "Errno" also makes "%!" magic such that each element of "%!" has a non-zero value only if
       $! is set to that value. For example:

           my $fh;
           unless (open($fh, "<", "/fangorn/spouse")) {
               if ($!{ENOENT}) {
                   warn "Get a wife!\n";
               } else {
                   warn "This path is barred: $!";
               }
           }

       If a specified constant "EFOO" does not exist on the system, $!{EFOO} returns "".  You may
       use "exists $!{EFOO}" to check whether the constant is available on the system.

       Perl automatically loads "Errno" the first time you use "%!", so you don't need an
       explicit "use".

CAVEATS

       Importing a particular constant may not be very portable, because the import will fail on
       platforms that do not have that constant.  A more portable way to set $! to a valid value
       is to use:

           if (exists &Errno::EFOO) {
               $! = &Errno::EFOO;
           }

AUTHOR

       Graham Barr <gbarr@pobox.com>

COPYRIGHT

       Copyright (c) 1997-8 Graham Barr. All rights reserved.  This program is free software; you
       can redistribute it and/or modify it under the same terms as Perl itself.