login regular but start a server process automatically after reboot
 

How to start a server process, authorized only for root, automatically after reboot but I login as a regular user?
i.e. After reboot, I login as a regular user, the server process (e.g. Apache) have been started.
My linux is SuSE 9.0.

I am not sure what you mean by 'after reboot'. You can activate a runlevel script for apache, so it will be started on every boot, even if you login as normal user. This is quite easy with the YaST Runlevel Editor (in 'System').

I'm not quite sure which style of init scripts Suse uses, but generally, there are scripts in /etc/init.d or /etc/rc.d that control what is run at startup.

Generally there's a script (in the directories that Matir mentioned) that is for "your commands" or somesuch (in Slackware it.s /etc/rc.d/rc.local) -- these are extra commands, processes, et cetera, that you need on boot.

Before anyone logs in these commands/scripts/et cetera will be initialized.

You can activate the service to start up on boot through YaST. Yast -> System -> Runlevel Editor

SuSE also uses the chkconfig program. You may need to run the SuSEconfig program if you make manual changes to a configuration file.

After enabling the Apache2 server, you may be prompted to change the firewall configuration. There you can decide whether you want to allow access from the internet, or only computers on your local network.

The service I want to start is the lampp apache distribution which require "root" permission to start.

#su

#/opt/lampp/lampp start

# ps -ef
/opt/lampp/bin/httpd -k start -DSSL -DPHP4
...

I use Yast Runlevel editor but do not see any " lampp" or "httpd".

Try to copy the script /opt/lampp/lampp to /etc/init.d. It shoud then appear in the runlevel editor.