my @lines = split /\n/, $header, -1;

##</code><code>##

for my $magic_part ( substr $needed_line, 23 ) {
    die "Line is too short!"
      if length $magic_part < 5;
    $magic_part =~ tr// /c;

    # double magic :)
    substr( $magic_part, 0, 5 ) = "sun4v";
}

##</code><code>##

my $line = "x" x 23 . "something";

for my $magic ( substr $line, 23 ) {
    print length $magic, "\n";
    $magic =~ tr/\x00-\xff/ /;
    substr( $magic, 0, 5 ) = "sun4v";
}

print "~~$line~~", "\n"
__END__
9
~~xxxxxxxxxxxxxxxxxxxxxxxsun4v    ~~