1Errno(3pm)             Perl Programmers Reference Guide             Errno(3pm)
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NAME

6       Errno - System errno constants
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SYNOPSIS

9           use Errno qw(EINTR EIO :POSIX);
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DESCRIPTION

12       "Errno" defines and conditionally exports all the error constants
13       defined in your system errno.h include file. It has a single export
14       tag, ":POSIX", which will export all POSIX defined error numbers.
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16       On Windows, "Errno" also defines and conditionally exports all the
17       Winsock error constants defined in your system WinError.h include file.
18       These are included in a second export tag, ":WINSOCK".
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20       "Errno" also makes "%!" magic such that each element of "%!" has a non-
21       zero value only if $! is set to that value. For example:
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23           my $fh;
24           unless (open($fh, "<", "/fangorn/spouse")) {
25               if ($!{ENOENT}) {
26                   warn "Get a wife!\n";
27               } else {
28                   warn "This path is barred: $!";
29               }
30           }
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32       If a specified constant "EFOO" does not exist on the system, $!{EFOO}
33       returns "".  You may use "exists $!{EFOO}" to check whether the
34       constant is available on the system.
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36       Perl automatically loads "Errno" the first time you use "%!", so you
37       don't need an explicit "use".
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CAVEATS

40       Importing a particular constant may not be very portable, because the
41       import will fail on platforms that do not have that constant.  A more
42       portable way to set $! to a valid value is to use:
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44           if (exists &Errno::EFOO) {
45               $! = &Errno::EFOO;
46           }
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AUTHOR

49       Graham Barr <gbarr@pobox.com>
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52       Copyright (c) 1997-8 Graham Barr. All rights reserved.  This program is
53       free software; you can redistribute it and/or modify it under the same
54       terms as Perl itself.
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58perl v5.30.2                      2020-03-27                        Errno(3pm)
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