I am using a perl script to read a text file and show that on a page using an iframe.
It is a sort of chat box.
Now I use a meta tag to reload/ refresh the page every 300 seconds.
To reload a pae that isn't updated is no use. It is better to only reload the page when it is updated. So I added an extra value to the reload command that will add the last changed time of the file.
<meta http-equiv="refresh" content="300; URL=http://www.test.nl/cgi-bin/calendar/calendar.cgi?chat_data=1&number=8&next=8&last_update=1148023591&refresh=1
How to only update/ refresh the page when the file last update time is changed.
And if it is not changed do not reload the page to save uptime.