Principle of PHP5 scheduled task offline function

To regularly update a file, the program runs automatically. two methods are found on the Internet: ignore_user_abort () and crontabignore_user_abort () functions with set_time_limit (0) and sleep ($ interval) the program can automatically run updates. Is there an instance below? To regularly update a file, phpignore_user_abort requires the program to run automatically. two methods are found on the Internet: ignore_user_abort () and crontab ignore_user_abort () functions with set_time_limit (0) and sleep ($ interval) to automatically run and update the program. Below is an instance As long as you run the above page, and then turn it off, the program will continue to run. In Linux, there is a simpler method, that is, the crontab command is used to schedule the execution of some commands at certain intervals. Crontab usage: crontab [-e |-l |-r] file name-e: edit task-l: Display task information-r: delete scheduled execution task information crontab format: * ***** example of the Command crontab to be run on the day, month, and week of the Command: */5 * lynx http://www.php100.com visits www.php100.com 0 8 * lynx http://www.php100.com visit www.php100.com 0 10 6*1-5 lynx http://www.php100.com 6 per month at every day www.php100.com 0 5 7 8 * lynx http: // www. php100.com visit www.php100.com at on January 1, August 7. A few special meanings: "*" indicates all the numbers in the value range, "/" indicates each meaning, "*/5" indicates every 5 units, "-" represents a number from a number to a number, "," separate several discrete numbers.