3. Now carry out the actual configuration by typing:
ln -s /opt/lampp/lampp S99lampp
ln -s /opt/lampp/lampp K01lampp
Now XAMPP should start and stop automatically if you boot or shutdown your machine.
That generally works, but the note about shutdown is wrong. Those links will stop and then start XAMPP on boot, and not stop it on shutdown.
Here's how I do it (on a Debian-based distro):
ln -s /opt/lampp/lampp /etc/init.d/lampp
ln -s /etc/init.d/lampp /etc/rc0.d/K01lampp
ln -s /etc/init.d/lampp /etc/rc1.d/K01lampp
ln -s /etc/init.d/lampp /etc/rc2.d/S99lampp
ln -s /etc/init.d/lampp /etc/rc3.d/S99lampp
ln -s /etc/init.d/lampp /etc/rc4.d/S99lampp
ln -s /etc/init.d/lampp /etc/rc5.d/S99lampp
ln -s /etc/init.d/lampp /etc/rc6.d/K01lampp
That stops XAMPP on entry to runlevels 0 (halt), 1 (single-user) and 6 (reboot), and starts it on entry to runlevels 2-5 (multi-user). The reason I have the extra link /etc/init.d/lampp is just for consistency with the other (non-XAMPP) links in the runlevels.