guns are not suitable for every situation though. that dialog from the irishman 'guns you charge , knife you runaway'

in what situation is a knife better than a gun apart from cutting veggies and fruits?

Idk of the details of that quote, but it does spring to mind that a gun is far better at range than a knife. So, closing that distance could be better than fleeing if your opponent has a gun and there is no cover for you to use while you escape (depending on the weapon and the wielder! I'd take my odds running away from, say, an amateur armed with a flintlock pistol... If it is a trained marksman with a rifle you'd be dead trying to run, whereas, if you are close, trying to close the distance and get control of the gun might - might - work). Increasing the distance between you and a person with a knife is always a smart move.

In the martial artists' minds, of course.