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Errno(3)               Perl Programmers Reference Guide               Errno(3)

       Errno - System errno constants

           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 <>

       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 v5.8.8                       2001-09-21                          Errno(3)