我们可以通过PHP脚本配置cron作业的时间间隔吗？

Question

Can we configure cron job's time interval through PHP script, so that the time interval should not be set manually, but through a PHP script, whether it takes time interval from Database or fixed (but from within the PHP code).
Thanks in advance

Answer 1

I think it is much better to let your application control the frequency of events instead of the cronjob. Let the cronjob run a certain action of your application every minute. The action then for example checks a database table named cronjobs and runs the jobs marked for running by either a frequency number or a timestamp.

If you do it like this, you can add new jobs programmatically from everywhere, eg via an cronjob interface. The solution is easier to maintain, to test and to document .

Answer 2

There are two ways. Either, re-create the crontab on every change of the desired value or have the cron job fire regularly, eg every minute, and test the starting condition from within the script.

Answer 3

如果有足够的服务器特权，则应该能够通过使用System （）从PHP脚本进行系统级调用来实现。

Answer 4

The best to do this, would probably be by writing a PHP script that is capable of creating a crontab -file (and running your script with sufficient privileges to do this).

This site offers a pretty good tutorial.

However, dependency on cron will make your code dependant on platforms that support cron . Thus another solution would be to implement the timed-execution-logic in PHP itself (ie loop the code, and check the time yourself).

You could combine the two solutions above, by creating a Scheduler -interface that you can give a script, and it will make sure it's executed at the appropriate times. This way you can implement it using cron on linux, but in another way on Windows:

interface Scheduler {
  function schedule($script);
}
class CronScheduler {
  function schedule($script) {
    append_cronjob($script);
  }
}

Though, I might be overdoing it here.

Answer 5

If you want to do this I would suggest you to use Message Queue Beanstalkd instead. It can do delayed put programmatic and is very fast. I advice you to use pheanstalk to talk the Beanstalkd.