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utf8::all(3pm) User Contributed Perl Documentation utf8::all(3pm)


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.


  • File::Find::utf8 for fully utf-8 aware File::Find functions.
  • Cwd::utf8 for fully utf-8 aware Cwd functions.


  • 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.

2022-11-20 perl v5.36.0