I've recently started using an .htaccess files when I'm updating clients domains with updates. I do this with the 503 error handler to let the search engines know that the site is just temporarily down and that it will be back soon. I guess I also do it so that visitors to the site know that the site is down. I've recently learned that it's possible to have a custom 503 error page just like a custom 404 page which is cool!
But my real question is what is the best way to go about "activating" maintenance mode on a domain?
Currently I've got two .htaccess files. One is the normal everyday one, has some https rules on it and some other stuff. The other .htaccess file I have stored on the server as .htaccess_upgrade. When I want to put the domain into maintenance mode I take the normal .htaccess file and rename it to .htaccess_normal and then I remove the _upgrade text from the .htaccess_upgrade file. I don't have a problem doing this, it just seems slow and cumbersome.
I know that it's also possible to do 503 errors with PHP but I'm still not sure how I could make this simpler, like just click a button to turn maintenance mode on or off.
So, basically I'm just looking for theories or suggestions or examples that have worked for you in the past.