I need to write a shell script in which I need to bounce the Tomcat server(it would possibly on anyone's system). Hence, I wanted to know how should I check if tomcat is ran as a service with "service tomcat6 start" or with the script "./bin/startup.sh"?
If this is for a production server: Assume that it's always started as a service. If you find out that it isn't: Find the person that started from the shell and fire them.
Hard words, but on production systems: Hand off, keep them operating according to a standard. If you automate the bouncing (restart): This is what you do.
Dangers when starting through startup.sh: The process will be started as whatever user executes the script - potentially lacking write permissions to the log and temp files, or ruining it for the next start through service tomcat start, when the service can't access those files any more.
Thinking of it: It might be a good idea to check (at least) the identity of the current user in startup.sh (or setenv.sh) and terminate if it's not the expected one. Thus effectively forbidding to ever run startup.sh as a regular user, including root.