*/5 * * * * （每5分钟执行一次）
0 20 * * * 每天 20点执行定时build
# every fifteen minutes (perhaps at :07, :22, :37, :52)
H/15 * * * *
# every ten minutes in the first half of every hour (three times, perhaps at :04, :14, :24)
H(0-29)/10 * * * *
# once every two hours every weekday (perhaps at 9:38 AM, 11:38 AM, 1:38 PM, 3:38 PM)
H 9-16/2 * * 1-5
# once a day on the 1st and 15th of every month except December
H H 1,15 1-11 *