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Manual Reference Pages  - Errno (3pm)

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Errno - System errno constants

CONTENTS

    use Errno qw(EINTR EIO :POSIX);

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.

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;
    }

Graham Barr <gbarr@pobox.com>

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.

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