cron_cheat_sheet

# * * * * * command to be executed
# - - - - -
# | | | | |
# | | | | ----- Day of week (0 - 7) (Sunday=0 or 7)
# | | | ------- Month (1 - 12)
# | | --------- Day of month (1 - 31)
# | ----------- Hour (0 - 23)
# ------------- Minute (0 - 59)
#
# @reboot	    Run once, at startup.
# @yearly	    Run once a year, “0 0 1 1 *”.
# @annually	(same as @yearly)
# @monthly    Run once a month, “0 0 1 * *”.
# @weekly	    Run once a week, “0 0 * * 0”.
# @daily	    Run once a day, “0 0 * * *”.
# @midnight	(same as @daily)
# @hourly	    Run once an hour, “0 * * * *”
# exemple : @daily /path/to/backup/script.sh

The crontab -e command will check the environment variables $EDITOR and $VISUAL for an override of the default text editor.
To change it :

export VISUAL=vim
#ou
export EDITOR=vim

search?q=cron&btnI=lucky