How to find out what was the referral url?

People come to my website from variety of other websites and I would like to know these referral 开发者_如何学JAVAurls? How can I do it in PHP?

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You can get the referrer using $_SERVER['HTTP_REFERER']. Note that it's very easy for the client to spoof this, so don't rely on it for anything important.

You can find out about other $_SERVER variables here.

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$ref = getenv("HTTP_REFERER");

or

$ref = $_SERVER['HTTP_REFERER'];

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Use the system variable:

$_SERVER['HTTP_REFERER']

Check this answer for more details.

Determining Referer in PHP