Give me a Brake

I want to remove my brake caliper to inspect it and, if defective, get a new/rebuilt one at the parts store with the core in hand so I don’t have to make two trips. My question is, how do I keep the fluid in the system so I don’t have to bench bleed the master cylinder if the fluid drains the MC dry? Is there a plug for brake lines? Thank for any help.

You should bleed the system no matter what. You do not have to bench bleed the master cylinder though. You can plug the line with some plastic and a rubber band or just a piece of shop towel anything will do.