Plan A: http://www.wikihow.com/Make-a-Guthook-Knife-from-an-Old-Saw-Blade Now if we lose public energy, then improvise as best you can.
Plan B: Buy the knife (or knives) you want ahead of time, and then store it (or them) for harder times.
Plan C is to use the knife (or knives) in the interim. Many already have knives in their kitchen area, and they are already being used. Many people already have ways to sharpen these knives routinely, too.