Errno(3p) Perl Programmers Reference Guide Errno(3p)
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 <
[email protected]>
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 v5.40.1 2025-04-13 Errno(3p)