Date question

I am creating a shell script and have a question about how to determine yesterdays date. In my script, I can determine today by:

today=`date '+%Y%m%d'`

but I am not sure how to determine yesterday. In other languages, I would just subtract one from today, but I don't know how to do that here. Please understand that I do NOT want to change the system date, I just want to determine the date for yesterday in a YYYYMMDD format. Any help would be greatly appreciated.

Please refer to the scripts section of the board. Perderabo (IIRC) has done all the work with calulating dates and put it there.

bakunin