The reason why burglars knock on the door is to see if someone is home before they attempt the break in.
The burglar wants to try to avoid any confrontation by confirming the house is not occupied.
The knocking on the door by the burglar is used to appear as them being innocent and to minimize the risk of being caught and by also assessing the security of your property and look for potential vulnerabilities.
Most burglars do not want to hurt you as a burglars main goal is to get into a place and steal what you have.
Burglars are often after stealing tools, money, Jewelry, televisions, computers or anything else you have that they want to steal.
Most burglars want to get into the place, steal what they want and then leave without being harmed or harming you.
If the burglar does want to hurt you then it is often due to them being scared of your appearance so they freak out and attack you.
If you're in your house and there's a burglar and you can safely exit the house it's best to get out of the house and call the police.
Only use deadly force if they intend to harm you and you have no option to get away from them.
You can't just shoot the burglar just because they are stealing and in your house and in some places you might be able to do that but other states have different laws on it.
Generally though if they are in your house and you're fearing for your life or your families life then you can sometime shoot them.
Sometimes simply pulling a gun on them will make them go away but it all depends on the burglar and not all burglars act the same and some may have a gun or other weapons and others don't.
Many burglars who break into houses and buildings try to avoid any contact with people although not everyone is like that.
If you do believe that the burglar or intruder means to harm you then you may have to defend yourself or your family.
If you do need to defend yourself you should make sure you have the necessary self defense skills and know how to use it.
If you arrive home and a burglar is in your house then you should not enter and call police instead.