crontabs are in the following format:
5 * * * * echo "hello world" # every 5th minite of a hour
NOTE: number in cron means every i-th, not every.
* * * * * every minute 12 * * * * every 12th minute on the hour 0,15,30,45 * * * * every 15 minutes 0 4 * * * every day at 4:00am 0 4 * * 2 */4 2-6 * * * every 15 minutes between 2 a.m. to 6 a.m. @hourly/@daily/@weekly/monthly/@yearly special syntax @reboot at reboot
crontab should be edited with crontab
crontab -e # edit current user's crontab crontab -l # list current user's crontab crontab -u # another user's
SHELL=/bin/bash HOME=/ MAILTO=”firstname.lastname@example.org”