use Encode;

sub write_to_file {
  my ($mode, $filename, $what) = @_;
  open (my $fh, $mode, $filename)
    or die "Couldn't open $filename for writing: $@";
  print $fh $what;
  close $fh;
}

my $iso_8859_1 = 'Österreich';
my $string = Encode::decode('iso-8859-1', 'Österreich');
my $utf8 = Encode::encode_utf8($string);

write_to_file('>', '_original', $iso_8859_1);
write_to_file('>', '_decoded', $string);
write_to_file('>:utf8', '_utf8', $utf8);