text file modification with perl

[dtmnuclear]

I need to run an executable a number of times with modified input decks. The input deck I use is fixed format and I need to replace line 80 for each of the different runs. I was wondering how to open the input deck, go to line 80, REPLACE the text, save the input deck, and then execute the code. Any help would be GREATLY appreciated as I have to make a number of these runs.

[KevinADC]

You already have replies on a couple of other forums.