While loop in bash script for svn

I have a bash script that Im using on my centos machine that checks out from subversion and puts everything onto my host machine.

I need to use some sort of loop, maybe a while loop, to make my script check for a new version in subversion every 5 minutes. If the version hasnt changed, sleep for another 5 minutes and check again.

If the version has changed, say from revision 15 to revision 16, I need it to run my script to export that new revision.

Can anyone help me create some sort of loop to satisfy that? Im not sure whats best; While, If-else, etc

Thank you!