plist is a simple program that uses the process status API to list currently running processes. plist will show the full path to a running executable, and has basic filtering so that you can search for specific processes. It returns values to the command shell that can be used to test whether a process is running.
plist is packaged in a zip file. Unzip it and put it anywhere you like; it has no dependencies.
plist is relatively straightforward to use. Type plist /? for instructions.