The date command outputs a newline after the date. That's expected because you get the same if you run the same command in a shell.

You can chomp() the variable to remove the trailing newline, but ...

Why don't you just get the date with perl alone in the first place, like this?

Code:

use Time::localtime;
$date_today = sprintf("%02d%02d%02d", (localtime->year+1900) % 100, localtime->mon+1, localtime->mday);

If you are willing to install extra module, there are even easier ways to generate arbitrary date strings.