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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 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 v5.16.3                      2021-02-02                        Errno(3pm)