PHP script as target of <a href="script here">?

I need to be able to have href links launch photoshop on a users machine and open the file referenced in the link. Is there a PHP mechanism that allows this sort of thing? Basically, I'd like to embed function calls in anchor tags like so (unless there is a better way to do it) echo "<a href=open_file_with_photoshop(\"path/to/photo/file.jpg\")>Click here to open file in Photoshop</a>"; I found the following sort of works... echo "<a href=\""; echo open_file_with_photoshop(\"path/to/photo/file.jpg\"); echo "\">"; ... but photoshop is launched when the page loads (before the user gets a chance to click the link) Subsequently, the links open the specified files as expected but the cursor doesn't recognize them as a link even though the browser renders them as normal looking <a> tags. Thanks for any help, Ken