PHP

Another technique for redirecting people to new pages is PHP, a scripting language that can be embedded in your HTML documents. This technique is normally used to redirect people to the new destination based on a variable value, for instance the browser used by the viewer or any other PHP variable.

Several important things to note about PHP scripts:

• PHP is case sensitive, print is different from PRINT.
• PHP statements appear between <? ?>.
• PHP statements end with a semi-colon (;).
• You can include comments in your PHP code by beginning the line or lines with // characters.
• Your PHP files should have a .php extension rather than a .html extension. If scripts have a .html extension the server will not know that they are PHP files and will not parse and execute the PHP commands.

Syntax is:

<?
header("Location: location");
exit;
?>

For example,

<?
header("Location: http://www.utexas.edu/its/");
exit;
?>

tells the browser to load http://www.utexas.edu/its/ and stop reading this string of code.

Note: remember to write this code before any output operation. Otherwise, your header will be generated by the Web server and this line would be interpreted as text.

Advantages

• Control over the redirection without contacting the system administrator.
• Correct URL address appears in the browser's location box.
• New location can be on a different server.

Disadvantages

• User is not informed about the site change.
• On ITS Web servers, files to be read from or written to must have the same ownership of the PHP script being executed, or the directory in which the script resides must be owned by the owner of the PHP script.
• Also, on ITS Web servers, PHP scripts cannot execute external system programs.

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