Errno(3perl)           Perl Programmers Reference Guide           Errno(3perl)
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.

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

           use Errno;

           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.

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.

perl v5.22.1                      2016-03-13                      Errno(3perl)