Add Prevent Sleep With The Caffeinate Command as a Mac TIL

mac/prevent-sleep-with-the-caffeinate-command.md

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+# Prevent Sleep With The Caffeinate Command
+
+MacOS has a built-in utility `caffeinate` that can programatically prevent your
+machine from sleeping. There are two kinds of sleep that it can prevent via
+_assertions_.
+
+> caffeinate creates assertions to alter system sleep behavior.
+
+The two kinds of sleep behavior are _display sleep_ and _system idle sleep_. An
+assertion to prevent display sleep can be created with `-d` and system idle
+sleep with `-i`.
+
+We can combine those to prevent both and then specify a duration (_timeout_)
+with `-t` (with a value in seconds).
+
+```bash
+caffeinate -d -i -t 600
+```
+
+This creates assertions with 10 minute timeouts for both display and system idle
+sleep.
+
+The `caffeinate` command is blocking, so if you want to start it in the
+background, you can do that like so:
+
+```bash
+caffeinate -d -i -t 600 &
+```
+
+See `man caffeinate` for more details.