Opening Bag of Milk on Shabbat

Question: Is it permissible to open a bag of milk on Shabbat by making a small hole with a knife or scissors as per during the week?
Answer: It is permissible with the condition that the hole is made in a imperfect manner without using scissors or a knife. If you must, you may start the tear with a scissor or knife and then continue with your hand or teeth (see Shemirat Shabbat Ke-Hilchata 9:3).