ZONE IS CRUEL WITHOUT KNIFE, AM I RIGHT?
But don't worry, there is simple solution.
In Cordon, in stalker village, there is one case in the old building.
Until you don't see stash in there in your PDA map, it is still empty.
But after while, when you check one dead body, stash appears and you can get a knife.
When you take that stash, knife will not appears in your inventory.
If you press "1" button, character will select knife. Enjoy.