litd

v1.0.0

Daemon for automatic management of keyboard and display brightness using applesmc light sensor (for Mac on Linux.)

When using litd, you take full responsibility for setting too large brightness values in config file and possibly damaging your display or keyboard or both.

Tested on Arch Linux (kernel 5.5.2-arch1-1), MacBook Pro (Retina, 15-inch, Mid 2015) (MacBookPro11,4)

Installation guide

Usage

Installation guide

litd has to run as you (to get your idle time properly)

If your system is not systemd based, you need to figure the permissions and auto start sections by yourself.

Prerequisities

To use litd your system has to fulfill all of these criteria:

1. Linux on a Mac.
2. Libraries: libXss and libX11 (for getting user idle time.)
3. Files (permissions):
   1. /sys/devices/platform/applesmc.768/light (o=r)
   2. /sys/class/backlight/intel_backlight/brightness (o=rw)
   3. /sys/class/backlight/intel_backlight/max_brightness (o=r)
   4. /sys/devices/platform/applesmc.768/leds/smc::kbd_backlight/brightness (o=rw)
   5. /sys/devices/platform/applesmc.768/leds/smc::kbd_backlight/max_brightness (o=r)
4. GCC compiler.

ii) and iv) need rw permissions which have to be set on every boot. If you use systemd, you can use the included brightness-perm.service (how to use it is explained later in this guide.)

If your system fulfills all of these criteria, you can continue in this guide and use litd.

Setup

Clone this repo where you want to have litd installed.

Make sure you have rw permissions on keyboard brightness file /sys/devices/platform/applesmc.768/leds/smc::kbd_backlight/brightness and display brightness file /sys/class/backlight/intel_backlight/brightness.

Permissions for keyboard and display brightness files need to be set on every boot. For this use units/brightness-perm.service. Put it in /etc/systemd/system/ and enable it.

$ systemctl daemon-reload
$ systemctl enable --now brightness-perm.service

Compilation

Compile litd (probably into bin/ directory) like this:

$ mkdir bin
$ g++ litd.c xidle.c daemonize.c control.c config.c -O3 -lXss -lX11 -o bin/litd

Generate config file

To generate default config file, simply run ./litd (where is config file located?)

Next you need to edit display_max, display_min, keyboard_max and keyboard_min values in config file. See litd.conf for determining values of these settings.

Auto start

Next edit units/litd.service to point at your compiled executable, put it in $HOME/.config/systemd/user/ and enable it as user unit.

$ systemctl --user daemon-reload
$ systemctl --user enable --now litd.service

Make sure you keep the -d option in your path (to start litd in daemon mode.)

Check that everything works.

Usage

litd has to run as you (to get your idle time properly)

Flags

-d to run in daemon mode (litd.pid file is located at the same location as config file)

$ ./litd -d

-v to run in verbose mode (not allowed in daemon mode)

$ ./litd -v

Config file

litd creates its config file (and .pid file in daemon mode) in a directory named litd/ whose location is determined based on $XDG_HOME_DIRS. If this variable does not exist or is empty, then default path $HOME/.config/ is used.

See litd.conf file for more info.

Signals

Sending signals to litd works only in daemon mode (litd -d)

litd ignores sensor value for reset seconds if you adjust brightness manually. It does this seperately for keyboard and display. You can reset this by sending SIGUSR1 to litd.

$ kill -SIGUSR1 litd_pid

You can reload config by sending SIGHUP to litd.

$ kill -SIGHUP litd_pid