Why I've got no crontab entry on OS X when using vim?

Question

I would like to use cron on my Mac. I choose it over launchd, because I want to be able to use my new knowledge on Linux as well. However, I cannot seem to get

Answer 1

I've never had this problem, but I create a ~/.crontab file and edit that (which allows me to back it up, Time Machine or otherwise), then run

crontab ~/.crontab

Has worked for me for 20+ years across many flavors of unix.