utf8::all - turn on Unicode - all of it


version 0.024


    use utf8::all;                      # Turn on UTF-8, all of it.

    open my $in, '<', 'contains-utf8';  # UTF-8 already turned on here
    print length 'føø bār';             # 7 UTF-8 characters
    my $utf8_arg = shift @ARGV;         # @ARGV is UTF-8 too (only for main)


The use utf8 pragma tells the Perl parser to allow UTF-8 in the program text in the current lexical scope. This also means that you can now use literal Unicode characters as part of strings, variable names, and regular expressions.

utf8::all goes further:

  • charnames are imported so \N{...} sequences can be used to compile Unicode characters based on names.

  • On Perl v5.11.0 or higher, the use feature 'unicode_strings' is enabled.

  • use feature fc and use feature unicode_eval are enabled on Perl 5.16.0 and higher.

  • Filehandles are opened with UTF-8 encoding turned on by default (including STDIN, STDOUT, and STDERR when utf8::all is used from the main package). Meaning that they automatically convert UTF-8 octets to characters and vice versa. If you don't want UTF-8 for a particular filehandle, you'll have to set binmode $filehandle.

  • @ARGV gets converted from UTF-8 octets to Unicode characters (when utf8::all is used from the main package). This is similar to the behaviour of the -CA perl command-line switch (see perlrun).

  • readdir, readlink, readpipe (including the qx// and backtick operators), and glob (including the <> operator) now all work with and return Unicode characters instead of (UTF-8) octets (again only when utf8::all is used from the main package).

Lexical Scope

The pragma is lexically-scoped, so you can do the following if you had some reason to:

        use utf8::all;
        open my $out, '>', 'outfile';
        my $utf8_str = 'føø bār';
        print length $utf8_str, "\n"; # 7
        print $out $utf8_str;         # out as utf8
    open my $in, '<', 'outfile';      # in as raw
    my $text = do { local $/; <$in>};
    print length $text, "\n";         # 10, not 7!

Instead of lexical scoping, you can also use no utf8::all to turn off the effects.

Note that the effect on @ARGV and the STDIN, STDOUT, and STDERR file handles is always global and can not be undone!

Enabling/Disabling Global Features

As described above, the default behaviour of utf8::all is to convert @ARGV and to open the STDIN, STDOUT, and STDERR file handles with UTF-8 encoding, and override the readlink and readdir functions and glob operators when utf8::all is used from the main package.

If you want to disable these features even when utf8::all is used from the main package, add the option NO-GLOBAL (or LEXICAL-ONLY) to the use line. E.g.:

    use utf8::all 'NO-GLOBAL';

If on the other hand you want to enable these global effects even when utf8::all was used from another package than main, use the option GLOBAL on the use line:

    use utf8::all 'GLOBAL';

UTF-8 Errors

utf8::all will handle invalid code points (i.e., utf-8 that does not map to a valid unicode "character"), as a fatal error.

For glob, readdir, and readlink, one can change this behaviour by setting the attribute "$utf8::all::UTF8_CHECK".



By default utf8::all marks decoding errors as fatal (default value for this setting is Encode::FB_CROAK). If you want, you can change this by setting $utf8::all::UTF8_CHECK. The value Encode::FB_WARN reports the encoding errors as warnings, and Encode::FB_DEFAULT will completely ignore them. Please see Encode for details. Note: Encode::LEAVE_SRC is always enforced.

Important: Only controls the handling of decoding errors in glob, readdir, and readlink.


If you use autodie, which is a great idea, you need to use at least version 2.12, released on June 26, 2012. Otherwise, autodie obliterates the IO layers set by the open pragma. See RT #54777 and GH #7.


Please report any bugs or feature requests on the bugtracker website.

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.


The filesystems of Dos, Windows, and OS/2 do not (fully) support UTF-8. The readlink and readdir functions and glob operators will therefore not be replaced on these systems.



  • Michael Schwern <>

  • Mike Doherty <>

  • Hayo Baan <>


This software is copyright (c) 2009 by Michael Schwern <>; he originated it.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.