ktsirig

Hello!
I am having a problem that I think is solved by using sessions and page refresh.
I have a page where the user enters data. The data are used as input for an external program that runs in the shell, irrelevant to PHP. When the program ends, all results are stored in a text file, which I open with PHP and parse the results so that the user sees them on screen.

So I have :

form.php => which contains the form
[....] => external program that runs in the background and creates temporary text file with the results
process.php => opens text file and prints the results

What I would like to do is something I have seen in many websites. I want to have an 'intermediate' page that will say for example "Please wait, we are processing your request".... This page will automatically refresh when the external program ends and then it will redirect to process.php file to show the results.
I think it is better to have such a page instead of 'stucking' to the initial page [form.php] during the processing time and then display the results.
Note that the external program can end in 1 minute, but it can last for 4 or 5 minutes if the user has submitted lots of data.
Any ideas on how to do this?