How to tell if a certain program is running?

[Craig Hagerman]

I am wondering if there is a simple way to programatically tell if a
given program is running. I want to write a bash script to check if a
program is running, then if not start it.

My first idea was to try to return grep the output from 'ps ax' but
even if a program isin't running grep will return the request you just
made. I am sure there is a more elegant way I don't know about.

Craig