We just moved into a split level house about 40 years old. This will be our first Christmas and I cannot figure out how to put up lights because we don't seem to have any outlets outside. I could buy socket adaptor and put it on one of my outside lights but I don't know if this would be safe or not. Suggestions welcome. Not enough time to get an electrician out to put in some outside sockets.
As long as you don't overload the fixture or the circuit, those socket adapters would be OK, especially for a temporary setup like Christmas lights. The key is making sure you're not overloading anything.
Figure out what else is on the circuit with the outside light, and what size breaker protects that circuit. Figure out what size wire is used inside the light - this will typically be smaller than the #14 used in lighting circuits. Determine the current capacity of that smaller wire, and keep the total load less than that capacity. Using LED bulbs will allow you to run more lights this way.
Of course, using an actual receptacle is the preferred option, so make sure you don't have any outside. Check around the AC unit for a receptacle, and near each entry door. Check in your garage (including on the ceiling, where an opener may be plugged in). Running extension cords all over is quite normal during the holidays.
You may prefer to run an extension cord from inside; just make sure that it isn't crushed when closing the window or door it passes through.
First of all talk to either an license electrician, an electrical inspector, or even an electrical engineer instead of asking the average person about wiring. And I would never put an extension cord under the garage door for it being pinched by the closing of the door. I went to electrician school, back in the 80's and had an electrical engineering with a bachelors degree in electrical engineering teaching the course, who had his own business with residential wiring. I am also a electronic engineering technologist with a background in residential wiring too. And my extensions cords that are made for the outside are water resistance to a certain point , they stand up to snow, rain, and if they would get to wet the GFI would trip shutting off the ground fault. Check with somebody who actually works in the field.
Another thing is that any electrical outlet according to the US Electrical Code has to be a ground fault circuit interrupter receptacle under the NEC (National Electrical Code, article 210-8 for it to be accessible to grade level, or the ground. Now most homes have GFCI breakers in the garage for several decades since that law was passed. But I still wouldn't put it under a garage door before checking with an electrical inspector in your local area where you live.