Caffeine-like utility to keep you MacBook awake with its lid closed | Hacker News Reader

Caffeine-like utility to keep you MacBook awake with its lid closed

github.com

17 pointsclash34 comments

Why download a third-party script when this feature is built into MacOS? Just run:

    sudo pmset -a disablesleep 1

to prevent macOS from sleeping. This works even when you close the lid and are on battery power. To re-enable normal sleep again, change the 1 to a 0.

1) Because you will eventually forget to reactivate it, which then leads to obvious problems.

2) Because you can for example be connected via ssh: You run the script and if your connection is disconnected, caffeinate+ shuts down the MacBook.

Edit: The API call that 'sudo pmset -a disablesleep 1' does is literally the first thing caffeine+ does. As soon as the lid closes the command is automatically reverted so you can't forget to do it yourself.

Both of those are trivial to do in a few lines of shell. There's no need to write or download a custom tool for this. I asked Opus to draft one up and it's just five lines long.

    #!/bin/bash
    [ "$EUID" = 0 ] || exec sudo "$0" "$@"
    pmset -a disablesleep 1
    trap exit HUP INT TERM
    trap 'pmset -a disablesleep 0; ioreg -r -k AppleClamshellState | grep -q "State\" = Yes" && pmset sleepnow' EXIT
    "${@:-read}"

How to use it:

    ./caf.sh              # stay awake until you press Enter
    ./caf.sh make build   # stay awake only while the command runs

Sleep is re-enabled when: the command finishes, the user presses Enter, on Ctrl-C, on SSH disconnect, or on kill (excluding SIGKILL). If the lid is closed when the command finishes, sleep is re-enabled and the Mac goes to sleep.

You say "No need to write a tool", then immediately write a tool. Brilliant :)

My first attempt was a shell script almost exactly like yours. Then I thought I want to be able to set SUID so I don't have to use sudo. This ruled out the shell script. I could have just done a bunch of 'system("pmset ...")' calls but thought I might as well use the native commands.

One catch I hit with disablesleep: lid-close sleep only fires once, at the moment you close the lid. If you set disablesleep back to 0 while the lid is already shut, the Mac doesn’t go to sleep. It drops to idle sleep, and any app holding an idle assertion (pmset -g shows them as “sleep prevented by …”) keeps it awake. I found mine hot in a bag two hours later. So if you script this, run “sudo pmset sleepnow” right after turning it back off, unless an external display is attached and you mean to stay in clamshell mode.

There are probably 20 of these at this point. I use amphetamine [1] (free on the app store). It has configurable timeouts with optional warnings/notifications, to reduce the ability for your MacBook to melt in your backpack. Can also have it disable when an app closes/download completes/battery percentage, and all sorts of triggers (like bluetooth presence, useful for backpack proximity).

[1] https://apps.apple.com/us/app/amphetamine/id937984704

Yeah, I obviously also did the research prior to implementing my solution.

I did not want GUI, just super simple caffeinate-like CLI. Also I wanted auto-shutdown afterwards.

Are those 20 free and open source as well? Name them then.

My mistake. Well over 20.

https://www.google.com/search?q=site%3Agithub.com+keep+mac+o...

First one I used was around 9 years ago. Nearly melted my backpack with the hot Intel CPU!

If you don't want to install anything, you can disable sleep with the built in tools: sudo pmset -a disablesleep 1

Yeah, most of these repositories contain more files than caffeinate+ has lines of code.

The API call that 'sudo pmset -a disablesleep 1' does is literally the first thing caffeine+ does. But is only part of the full solution: As soon as the lid closes the command is automatically reverted so you can't forget to do it yourself. Also if you kill caffeinate+, the MacBook is put to sleep when the lid is still closed.

Yes, most of the very many that you didn't know existed just a moment ago also handle that tricky case of restoring normal operation.

Bold accusation ;)

You forgot to argue about the LOC vs file count issue.

Also, you are wrong: None does auto sleep on script exit.

Oops, didn't follow user names. My mistake.

And, I've been using these for around 9 years. A few I tried most definitely did re-enable on exit. Not sure why file count is a concern, or especially LOC (a truly horrendous metric to target, with the outcome being unintelligible code golf when optimized for). All that I used were exactly one file I was concerned with: a binary or shell script.

This has become strange. Cheers!

Obviously code-golfed LOC is bullshit. 50 files and GUI for a near-trivial functionality is excessive, though.

I mean, yeah...

https://github.com/search?q=caffeinate+lid+close&type=reposi...

What are you talking about? It’s a one line terminal invocation. These apps are utterly useless. Of course there’s a million open source ones.

Switching between headphone output and speaker output on my system is also just one line. I have no idea what that line is because I created a toggle-able icon in waybar which is a really simple script that switches between the two outputs and shows me the correct icon. I didn't need a "tool" to do it, but the packaging and UX are far better than popping up a terminal any time I want to do this.

Can your one line terminal invocation automatically put the MacBook to sleep when you are connected via ssh and the connection is lost?

Technically one line ;)

    sudo bash -c 'trap "pmset -a disablesleep 0" EXIT; s=; while :; do if lsof -nP -iTCP:22 -sTCP:ESTABLISHED >/dev/null 2>&1 || pgrep -xq ssh;
  then n=1; else n=0; fi; [ "$n" != "$s" ] && pmset -a disablesleep $n && s=$n; sleep 10; done'

This is neat. I ended up having to buy one of those dummy HDMI dongles to keep my MacBook awake so that I could remote into it. If it thinks there's an external monitor attached, it won't sleep. Or at least you can set it up that way.

Windows has been surprisingly good about this (lid closed, laptop awake). I have a number of always-closed laptops deployed for customers (+ mother in law). Some are desktops that can be easily moved; others are on-prem devices that are left alone to handle certain tasks.

This isn't my first reading about the struggles MacBook users have here. It is bizarre to me that Apple doesn't natively and reliably support closed+awake devices; it feels like they've dug in their heels and I can't imagine why.

Windows is so good at this that it refuses to let my work laptop sleep when I close it and put it in my backpack no matter how many settings I try tweaking.

For the desk setup scenario, it's less of a problem since they'll stay awake in clamshell if they've got a power source and are hooked up to an external monitor. I've used my personal MacBook in a hybrid home/work setup like this for years without issue. It's only if you want clamshell on battery and/or with no external monitor that tools like this become necessary.

So, you folks know that there is a built-in CLI utility for this on macOS, right?

``` $ which caffeinate /usr/bin/caffeinate ```

And there’s a man page for it?

``` $ man caffeinate

CAFFEINATE(8) System Manager's Manual CAFFEINATE(8)

NAME caffeinate – prevent the system from sleeping on behalf of a utility

SYNOPSIS caffeinate [-disu] [-t timeout] [-w pid] [utility arguments...]

DESCRIPTION caffeinate creates assertions to alter system sleep behavior. If no assertion flags are specified, caffeinate creates an assertion to prevent idle sleep. If a utility is specified, caffeinate creates the assertions on the utility's behalf, and those assertions will persist for the duration of the utility's execution. Otherwise, caffeinate creates the assertions directly, and those assertions will persist until caffeinate exits.

     Available options:

     -d      Create an assertion to prevent the display from sleeping.

     -i      Create an assertion to prevent the system from idle sleeping.

     -m      Create an assertion to prevent the disk from idle sleeping.

     -s      Create an assertion to prevent the system from sleeping. This assertion is valid only when system is running on
             AC power.

     -u      Create an assertion to declare that user is active. If the display is off, this option turns the display on and
             prevents the display from going into idle sleep. If a timeout is not specified with '-t' option, then this
             assertion is taken with a default of 5 second timeout.

     -t      Specifies the timeout value in seconds for which this assertion has to be valid. The assertion is dropped after
             the specified timeout. Timeout value is not used when an utility is invoked with this command.

     -w      Waits for the process with the specified pid to exit. Once the the process exits, the assertion is also released.
             This option is ignored when used with utility option.

EXAMPLE caffeinate -i make caffeinate forks a process, execs "make" in it, and holds an assertion that prevents idle sleep as long as that process is running.