"open or reload" html doc from command line?
Check out LiveReload. It is an app that watches your HTML files and can automatically for reload the pages in your browser. LiveReload can also do other things like automatically recompile SASS files to CSS and then reload the browser. 

In addition to the app at the link above, LiveReload is available on GitHub under a "Open Community Indie Software License" which is not quite open source, but does include a dead man clause to convert to MIT if no new binary updates come out for two years. https://github.com/livereload/LiveReload