I just recently asked this question: https://stackoverflow.com/questions/6359367/running-a-bash-program-every-day-at-the-same-time
The solution of using crontab -e to create a job worked very well and my script worked fine.
However, I found that once I exited the terminal, that job was deleted. How can I create a job mediated by cron that will work every day at the same regardless of if I exit the terminal or even turn off my computer (assuming my computer is turned back when the cron job is scheduled to execute)
cron is permanent. So the accepted answer given in the linked question would run the script at 7 AM everyday. It has nothing to do with if you are logged in or not.