backup without closing programs that are opening files for editing, and detect unsaved open files?

Is it possible to do backup without closing programs that are opening files for editing?

I would like to do backup without closing programs that are opening files that I am reading or writing. I usually open many text files in emacs in different terminal tabs, and pdf files in pdf editors, for a long period of editing, so I don't want to close the programs for keeping what files and where in them I am working on.

Most of the time I save changes immediately after I make some. But I might miss to save them sometimes. Should I check that manually, or is there some program to do that?