Errno(3)

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.