# errno(3) - man - phpman

> **TLDR:** Look up errno names and descriptions.
>
- Lookup errno description by name or code:
  `errno {{name|code}}`
- List all errno names, codes, and descriptions:
  `errno {{-l|--list}}`
- Search for code whose description contains all of the given text:
  `errno {{-s|--search}} {{text}}`
- Search for code whose description contains all of the given text (all locales):
  `errno {{-S|--search-all-locales}} {{text}}`

*Source: tldr-pages*

---

[Errno(3perl)](https://www.chedong.com/phpMan.php/man/Errno/3perl/markdown)                      Perl Programmers Reference Guide                      [Errno(3perl)](https://www.chedong.com/phpMan.php/man/Errno/3perl/markdown)



## 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](https://www.chedong.com/phpMan.php/perldoc/Errno%3A%3AEFOO/markdown)) {
               $! = &[Errno::EFOO](https://www.chedong.com/phpMan.php/perldoc/Errno%3A%3AEFOO/markdown);
           }

## 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.



perl v5.34.0                                 2025-07-25                                 [Errno(3perl)](https://www.chedong.com/phpMan.php/man/Errno/3perl/markdown)