How can you plug a small hole in a copper pipe?
Yes, in an emergency, you might plug a small leak for a few hours, BUT don't leave it patched for long! I once used a piece of car radiator hose, slit and held in place with a hose clamp over a pinhole leak. It seemed to worked nicely, so I grew overconfident and left it. A few days later I came home to find water an inch deep in the basement: the pressure popped the patch. It's pretty easy to cut copper pipe with a tubing cutter and to insert a short piece with two couplings, if you can solder. Of course, use lead-free solder; protect the area behind and above the pipe to prevent burning down your house. Another alternative: cut the pipe and add compression fittings.This is especially useful near a fixture, since you can add an approved flexible hose directly to the fixture's inlet valve.
The epoxy that Billy Mays shills on TV. Or go to the hardware store and buy some. Or you can cut the pipe and install a coupling at that spot. What caused the hole? That could have a bearing on how to fix it.
Try cutting at the hole and install a coupling. However a hole could indicate the pipe has eroded over the years. If this is the case you will know when you try to cut it. At that point you will need to replace a section of pipe.
