print header('application/pdf'), do {
    open my $fh, '<:raw', 'minimal.pdf' or die "D'Oh! $!\n";
    local $\;
    <$fh>;
};

##</code><code>##

print header('application/pdf');
{
    open my $fh, '<:raw', 'minimal.pdf' or die "D'Oh! $!\n";
    local $\;
    print <$fh>;
};

##</code><code>##

use File::Copy 'copy';
print header('application/pdf');
copy 'minimal.pdf', \*STDOUT or die "D'Oh! $!\n";