It is usually instructed to introduce new cron jobs through command lines; but I found it easier (with a better control of current cron tasks) to manually edit (in text editor) the user cron file like /var/spool/cron/crontabs/root
.
Is it dangerous to edit the file in text editor?
The comments in the default file is confusing. The first line says
# DO NOT EDIT THIS FILE - edit the master and reinstall.
But the fourth line says
# Edit this file to introduce tasks to be run by cron.