You can most certainly use a knife to open a can, as we mentioned above, but you want to be extra careful where you hold the knife. Since once you open the can the edge of the lid will be sharp, as well as the knife you are holding in your hand.
In all the steps above, if you want to take extra caution, you can wear a pair of safety gloves to protect your hands. Chances are, if you are opening a can in an emergency, you will not have safety gloves. The key is to work slowly and steadily.