Sometime crontab in Linux or Unix can not run some program. Because the environment of crontab is not as same as that of system. If you want to know the difference between those two environments settings. look up /etc/cron.d/anacron file and ~/.profile and ~/.bashrc and xxxx. I can not remember all of them. /etc/cron.d/anacron file is just for crontab. ~/.profile and ~/.bashrc is for system. If you want to know more, search “linux environment file” in Google.
I think to find all difference between two environment is waste time obviously. Another method is write own timer codes. So Here is my solution:
Write your own code will bring new bugs in your solution. Another drawback is spending your own time and this timer is not in common. However, you can control it!