The relevant documentation is here:

http://www.apachefriends.org/en/xampp-linux.html

Stop any previous running version of XAMPP with this:

sudo /opt/lampp/lampp stop

It may be a best practice to uninstall any previous version of XAMPP for a “clean install” with this:

sudo rm -rf /opt/lampp

Install the new version from the archive with this:

sudo tar xvfz xampp-linux-1.6.6.tar.gz -C /opt

Start the new version of XAMPP and set the security with this:

sudo /opt/lampp/lampp start

sudo /opt/lampp/lampp security

The practice here is to stop the FTP server (after setting a password) with this:

sudo /opt/lampp/lampp stopftp

The basics are now in place. From here MySQL databases are generated in loaded. And a script is run to generate symbolic links from /opt/lampp/htdocs to my local development web sites in my home directory (because XAMPP configures Apache to follow symbolic links by default).