Here's a challenge. I want to change the screen saver on a mac mini, running OSX, from a browser anywhere in the world.

You may well ask why ... the screen of the mac mini is to be visible at Well House Manor where it will provide an information screen at the front door when it's not otherwise in use, and we want it to say things like "Sorry - no Vacancies" and "Welcome to the Chamber of Commerce"

Task achieved! Using PHP ... and Perl ... and Web2 technology. With a smattering of OSX!

Here's the control widget on our web page ... the page is in PHP and this particular widget is only displayed to staff members who are logged in - if you look at our Staff Resources Page you won't see it.

And the PHP that's run when you press the update button:


if ($_POST[door] == 12) { // Door Status changed
  $ds = $_POST[doorst];
  $fho = fopen("door.txt","w");
  fputs ($fho,stripslashes($ds)."\n");
  fclose ($fho); // Host and Port changed for security
  $done = file("http://zzz.wellho.net:8080/cgi-bin/dodo.pl?$ds");
  }

That piece of viewing software was called a controller on the Mac - which is running as a Web Server on a port enabled on our firewall, and redirected with NATS to the Mac Mini.

The Perl software dodo.pl looks like this:

#!/usr/bin/perl
print "content-type: text/html\n\n";
print "Changing Page";
`rm -rf /Users/lisaellis/FrontDoor`;
`cp -r /Users/lisaellis/$ENV{QUERY_STRING} /Users/lisaellis/FrontDoor`;
open (FH,"ps aux|");
while (<FH>) {
  if (/ScreenSaverEngine/) {
  @n = split;
  kill 9,$n[1];
  print "$n[1]<br>";
  }
}
sleep 1;
open (FH,'|/System/Library/Frameworks/ScreenSaver.framework/Versions'.
'/A/Resources/ScreenSaverEngine.app/Contents/MacOS/ScreenSaverEngine' );
close FH;
print "Changing Page";

And there's also a standalone version here if you want to download a copy for your own use.

You'll notice - typical use of PHP to front a web application, typical use of Perl as "glueware", and typical use of a Unix / Linux / OSX utility - in this case Mac's ScreenSaverEngine - to do the oddball job we needed.
(written 2008-05-06 17:49:19)

 P258 - Perl - Solaris, OSX and Linux
H307 - PHP - Web2 and caching
A164 - Web Application Deployment - Services and Regular Jobs

Back to Lua - a powerful, up and coming scripting language

Previous and next or Horse's mouth home

Forward to Kiss and Book

Providing exceptional service - and carrying on doing so.
What to do if the Home Page is missing
Spring in Devizes
Kiss and Book
Changing a screen saver from a web page (PHP, Perl, OSX)
Lua - a powerful, up and coming scripting language
Looking back through some photos
To provide external links, or not?
A short introduction to our courses
Gant charts - drawing them with a PHP script
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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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