open(my $fh, '<', $filename);
binmode($fh);

##</code><code>##

open(my $fh, '<:raw', $filename);

##</code><code>##

$, = ' ';
$\ = "\n";

open(FH, '<', '/dev/null');
print(PerlIO::get_layers(FH));          # --> unix perlio

##</code><code>##

open(FH, '<', '/dev/null');
binmode(FH);
print(PerlIO::get_layers(FH));          # --> unix perlio

##</code><code>##

open(FH, '<:raw', '/dev/null');
print(PerlIO::get_layers(FH));          # --> unix