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Errno(3pm)                            Perl Programmers Reference Guide                            Errno(3pm)



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 v5.16.2                                     2013-08-25                                       Errno(3pm)