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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.
       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 AT 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 v5.26.3                      2023-05-18                        Errno(3pm)