macosxhints.com – 10.5: Migrate crontabs from 10.4
n Mac OS X 10.4 (and earlier?), crontabs (the lists of tasks scheduled with cron) were stored in /var/cron/tabs. However, in 10.5, they are now stored in /usr/lib/cron/tabs, and the installer doesn’t seem to move any existing files from the old to the new location. So, the easy way to bring your old crontabs across is to run the following command in a Terminal:
sudo mv /var/cron/tabs/* /usr/lib/cron/tabs
Note that this command will replace any crontabs you’ve edited or set up since upgrading to Leopard with the version you had in Tiger; if you think there’s likely to be a clash, it would be a good idea to open the old files in a text editor and copy-and-paste the entries across to your new crontab (using crontab -e) instead.