guess-xlate.pl

#!/usr/local/bin/perl

use strict;
use warnings;
use Encode;
use IsUTF8 'isUTF8';

binmode(STDIN);
binmode(STDOUT);
binmode(STDERR);
no warnings 'uninitialized';

my $fallback = 'windows-1252';

if (@ARGV) {
    # testing by only showing questionable output
    while (<STDIN>) {
        my $result = isUTF8($_);
        print STDERR $_ if $result;
        print encode_utf8(decode($fallback, $_)) if not defined $result;
    }
}
else {
    # the real thing
    while (<STDIN>) {
        my $result = isUTF8($_);
        print, next if defined $result;
        print encode_utf8(decode($fallback, $_)) if not defined $result;
    }
}