python定时程序（每隔一段时间执行指定函数）

import time  
def print_ts(message):  
    print "[%s] %s"%(time.strftime("%Y-%m-%d %H:%M:%S", time.localtime()), message)  
def run(interval, command):  
    print_ts("-"*100)  
    print_ts("Command %s"%command)  
    print_ts("Starting every %s seconds."%interval)  
    print_ts("-"*100)  
    while True:  
        try:  
            # sleep for the remaining seconds of interval  
            time_remaining = interval-time.time()%interval  
            print_ts("Sleeping until %s (%s seconds)..."%((time.ctime(time.time()+time_remaining)), time_remaining))  
            time.sleep(time_remaining)  
            print_ts("Starting command.")  
            # execute the command  
            status = os.system(command)  
            print_ts("-"*100)  
            print_ts("Command status = %s."%status)  
        except Exception, e:  
            print e  
if __name__=="__main__":  
    interval = 5  
    command = r"ls"  
    run(interval, command)