Not quite what you're asking, but back in the days of DOS, I did something this with a journal batch file I wrote. DOS (And even Windows now) runs a line from

Not quite what you're asking, but back in the days of DOS, I did something this with a journal batch file I wrote. DOS (And even Windows now) runs a line from a batch file, and the re-opens the file to read the next line. Makes it super easy to edit files that are running, and even easier back in the days of DOS when you had edlin to help you do the editing. My script would store state, options, journal entries, and other things I've long forgotten about in itself. Of course, it all came to a crashing halt when it managed to destroy itself.