To put it quite simply: anymore, there is no need to be installing an all-to-common tool called Caffeine. Apple has taken the liberty of saving us the legwork, and went ahead and included a handy little binary in macOS. As far as the man page is concerned, caffeinate allows one to…

prevent the system from sleeping on behalf of a utility

…which succinctly explains why caffeinate is a bit more useful than Caffeine insofar that its much more customizable. What if we don’t care about customizability, and we just want to mimic the same Activate For: <LengthOfTime> functionality that Caffeine has?

You got it!

caffeinate -t <Seconds> # Prevent idling for a specified time

caffeinate # Prevent idling indefinitely

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But if you’re like me… you like to tinker.

For instance, say you wanted to run a test which will take 6+ minutes to complete. During this time, you plan on getting into a lengthy thumb-war with your co-worker. The only issue is that your company’s IT department has booby-trapped secured your computer with a Chef cookbook to ensure that the system locks after 5 minutes of inactivity.

Enter: caffeinate

I’ll employ the ‘Show, don’t tell’ method here, and give you a glimpse what this looks like in real life:

What’s going on here?

On the right terminal we call caffeinate and pass it another command, chef-client, caffeinate then forks a process and executes chef-client within it. But we want proof, right? So, then we run ps to grab the PID for caffeinate, then throw the PID into top to monitor its status. As you can see, when the forked chef-client process ends, as does caffeinate.

We now have achieved a means by which we can ensure the system will not idle so long as its forked process is still running.