如何处理其中具有多种编码的文件？

Question

I have a small program to order and sort email messages, outputting to a textfile using $msg->decoded->string . The perl program outputs to stdout , and I redirect it to a txt file. However, gedit is unable to open this text file because of a character set problem, and I would like to know how to restore or set a character set with perl.

The program is now thus:

#!/usr/bin/perl
use warnings;
use strict;
use Mail::Box::Manager;

open (MYFILE, '>>data.txt');

my $file = shift || $ENV{MAIL};
my $mgr = Mail::Box::Manager->new(
    access          => 'r',
);

my $folder = $mgr->open( folder => $file )
or die "$file: Unable to open: $!\n";

for my $msg ( sort { $a->timestamp <=> $b->timestamp } $folder->messages)
{
    my $to          = join( ', ', map { $_->format } $msg->to );
    my $from        = join( ', ', map { $_->format } $msg->from );
    my $date        = localtime( $msg->timestamp );
    my $subject     = $msg->subject;
    my $body        = $msg->decoded->string;

    # Strip all quoted text
    $body =~ s/^>.*$//msg;

    print MYFILE <<"";
From: $from
To: $to
Date: $date
$body

}

However I get the same problem that I am unable to open the file with gedit, even though it works with vi or such. If there are non unicode characters in the file, would this break it?

Answer 1

Different messages probably are in different encodings. Probably gedit detects it as UTF-8, but later finds out that parts of the file aren't UTF-8. Mixed files like this are major PITA.

The best (perhaps only) solution is to check for the content type ( $message->contentType ) and convert everything to UTF-8.

Answer 2

If you are simply redirecting Perl's output, then Perl will have a difficult time producing a decent file.

You should try writing the file directly from Perl.

You should also check whether you really have an encoding problem or whether characters that simply don't belong in your file still end up there. Use vi or a hex editor or simply hexdump to do that.

Answer 3

You can use the IO layers facility. Open a file like this to specify the encoding:

open my $fh, '>:encoding(UTF-8)', $file;

Or you can use use binmode() to alter an already opened filehandle:

binmode(STDOUT, ':encoding(UTF-8)');

Of course, you can set other encodings than utf8, and there's plenty of other options, too. Just look in the documentations for open and binmode. Maybe IO::File is worth a look, too:

perldoc -f open
perldoc -f binmode
perldoc IO::File