Here's a very simple script to rotate your $BSE/log/olg.* files into $BSE/olg. The script has been greatly simplified to make it more generic.

Possible suggestions to enhance the script:
(error) logging
introduce support for multiple $BSE
archive only specific type of log files (e.g. log.oracle7/8 etc)

Please report any possible syntax errors!

See: http://www.baanboard.com/node/1768