SQL*Plus debugging?  Is there a way to step through the SQL Script?

Hi I have a colleague who has a SQL Script that she runs in Crystal Reports.  I need this similar script to run on our AIX box for a certain program.  It runs fine in Crystal, but it just hangs on our IBX AIX box.

It has like 14 SELECT Statements.  Is there a way I can step through this script in SQL, like a debug tool, so I can see why it is running a long time or failing without me knowing?  I wish there was a log file or something?  Is there??

Thanks in advance for help!