pg_dump warning format?

Hello, I'm currently working on an automated data archival script that will dump an existing archive db, drop it, recreate it from a template, and then fill it with any data ready to be archived from our production db.  My question here is:  What is the format of the warnings and/or errors that pg_dump will spit out on standard error?  Does redirect_stderr set in the config file affect the pg_dump utility?  Basically I need a way for my script to know if it needs to abort because there were issues with the dump before it follows through with the drop db...