To start XAMPP simply call this command:
sudo /opt/lampp/lampp start
You should now see something like this on your screen:
Starting XAMPP 1.8.2...
LAMPP: Starting Apache...
LAMPP: Starting MySQL...
Ready. Apache and MySQL are running.
If you get any error messages visit our community pages for help.
Also, note that there is a graphical tool that you can use to manage your servers easily. You can start this tool with the following commands:
sudo ./manager-linux.run (or manager-linux-x64.run)