Why does getallheaders() say undefined function?

How To configure to use getallheaders()

[kashyap rajput]

The getallheaders() is not working on our server , Our servers run php as cgi modules through the phpsuexec module. please provide solution for this.

[eelixduppy]

apache_request_headers [us3.php.net] (or getallheaders)is only supported when PHP is installed as an Apache module.

You can check the user-contributed noted for a possible solution.