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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.









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