http://www.linuxidc.com/Linux/2014-03/97555.htm
程序功能：指定一个或者同时多个固定的延迟（例如，5mins, 1hour,1 day, 1 week）,程序按照这个指定的延迟定时循环执行某个work
from datetime import date, time, datetime, timedelta
def work():
print "hello world."
def runTask(func, day=0, hour=0, min=0, second=0):
# Init time
now = datetime.now()
strnow = now.strftime('%Y-%m-%d %H:%M:%S')
print "now:",strnow
# First next run time
period = timedelta(days=day, hours=hour, minutes=min, seconds=second)
next_time = now + period
strnext_time = next_time.strftime('%Y-%m-%d %H:%M:%S')
print "next run:",strnext_time
while True:
# Get system current time
iter_now = datetime.now()
iter_now_time = iter_now.strftime('%Y-%m-%d %H:%M:%S')
if str(iter_now_time) == str(strnext_time):
# Get every start work time
print "start work: %s" % iter_now_time
# Call task func
func()
print "task done."
# Get next iteration time
iter_time = iter_now + period
strnext_time = iter_time.strftime('%Y-%m-%d %H:%M:%S')
print "next_iter: %s" % strnext_time
# Continue next iteration
continue
# runTask(work, min=0.5)
runTask(work, day=1, hour=2, min=1)
