On the web at O'Reilly . Create a form, and point it at your environment program. Saves the data from the form to the file. Use the name of your script without the .pl with an .data. If the file already has data in it, append the new data to the file.
Time stamp the entries in the file.
Deals with race conditions by locking the file on write. Critical section problems related to reading the file are also possible, but in this case, not worth worrying about. Processes the data in name .data and displays the data in a table. Compute the average of the temperature fields. Include this information on your page.