PHP time timer, how to solve

PHP Time Timers
Please help the master, PHP how to get time timer, that is, every time to execute the program?

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PHP doesn't seem to have it,
Should be in the JS, or under the Linux/unix can be achieved!
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Use Sleep () to set the interval time, and then run the program as a command line.
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The simplest way to do this is to judge the time in the code, and if so, run it. If it is a static page, it can be started with JavaScript src= ' xxx.php '. If there is a visitor, no visitors will be able to run.
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Write a planning task on it, win Linux can be, and then decide when to decide at what time
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1. You can use for and then add a sleep
2. Or do a scheduled task in win
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First understand the principle of the web and then send the post.
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Well, use the sleep function. ~~~~~~~~
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Not a real problem, I have encountered such a problem. Or Ajax to do, or system timed tasks. Sleep will make PHP always have a process in, feel uncomfortable
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Cronjob cronjob Cronjob
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It's best to do it in Windows or Linux.
If it's a rented host, it's not going to work.
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Php
Look at Commet technology.
Inside the Loop +sleep ()

Js
Setimeout ();

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