[X-Unix] Command to find if a certain app is running?

[Jerry Krinock]

Does anyone know if there is a command to find if a certain app is  
running?

I know one way to do this would be via osascript/AppleScript,

    tell application "System Events" set allApps to every application  
process

and then parse the list returned but I'd like to avoid the backslash- 
escape hell of osascript if possible.

Is there a command-line interface to System Events?

Thanks,

Jerry Krinock

P.S.  More generally, is there a way to search for "a command that  
will do XYZ" on OS X?  Example: Earlier today, I wanted to read/write  
user preferences but had difficulty remembering the command name  
'defaults'.