[plt-scheme] exception handling

I wish to execute a command and trap the exception it raises on
failure - I'm not interested in the exception, just don't want my
script to fail. After reading about call-exception-handler in the docs
I am still not clear how to do this.

I've got (call-with-exeption-handler f thunk) but trapping the error
with the function f doesn't stop the script from failing.