Here’s a nifty tool that does something I never really gave thought to: entr.
Short for “event notify test runner,” entr watches a file or directory, and if anything in that list changes, it executes a command. And then watches again.
Simple and clever. So while you’re editing an HTML file, at every write, you could trigger your browser to refresh.
Every time you change a line of source code and save it, you could recompile a program. Every time you add a line to a list of names, you could update a sorted version.
The home page has a lot of ideas that go much deeper than my trivial ones. And entr has a few command-line options that will satisfy peculiar cases.
Best of all, updated a little over a month ago. If you have ideas or questions, the developer might like to hear from you on this one. Enjoy.