Had some problems with my cronjobs (Yes, I know that they are deprecated) on my iMac machine that I recently upgraded to Mavericks on. Did some research and found this.
touch ~/.crontab sudo vi ~/.crontab
At this point, vi editor should open, edit your crontab, then exit out
(Taken from http://robosights.wordpress.com/2014/02/10/getting-cron-to-work-on-mavericks/)