如何在php脚本中编写和执行cron job命令？

Question

I'm trying to execute a cronjob command from the script for this I'm writing below code, but nothing is happening.Can someone please help me out here.

$query ="INSERT INTO master_schedule_email(date, time,active_status) VALUES ('$date','$time','1')";
$exec = mysql_query($query) or die ("Error in Query".mysql_error());

    $minute = date ('i' , strtotime($time)); 
    $hour = date ('H' , strtotime($time));
    $date = date ('d' , strtotime($date));
    $month = date ('m' , strtotime($date));

$croncommand = "$minute $hour $date $month * monthlyautomaticmail.php";
exec($croncommand);

Here, I want to run the cron job command at the exact time and date which is inserting to the db table.

May I know is this the correct way to schedule a cronjob from php script?

I thought this is how we execute a terminal command from php script but I'm getting nowhere.Please someone help me out here. Thank you.

Answer 1

Assuming you want to schedule new cronjobs, this is not the way to go about it.

I suggest creating a database table for scheduled jobs with a date field for when they should be executed and a date field for when they were last executed. Then you manually create a cronjob to run a script that checks the new table to see if there are any jobs that are past their due date (scheduled_datetime > current_datetime && last_execution_datetime < scheduled_datetime). If so, it runs them and updates the last_execution_datetime to the time and date of the execution.