LIGHT(1)

💡 light — a program to control backlight controllers 💡

okay bestie, gather round, because this one is actually about your screen being too damn bright at 3am 🫶

✨ SYNOPSIS ✨

light [OPTIONS] [VALUE]

🌈 DESCRIPTION 🌈

so light is a program to control backlight display and keyboard controllers under GNU/Linux. yes, both. screen brightness AND your lil keyboard glow. iconic behavior tbh 💅

here's what makes it eat:

• Operates independently of X (X-Window) — she does not need your whole graphics stack to function, no cap
• Can automatically figure out the best controller to use, making full use of the underlying hardware — she does her own research fr fr
• Supports a minimum cap on the brightness value, because some controllers set the display to be pitch black at a vaĺue of 0 (or higher) 😭 like genuinely unreadable, zero stars

---

👑 COMMANDS 👑

these are the unique commands, and they are giving main character energy:

• -H, -h — Show help text and exit 🎀
• -V — Show program version and exit
• -L — List available devices (the roster. the lineup. the girls.)
• -A — Increase brightness by value ⬆️✨
• -U — Decrease brightness by value ⬇️
• -S — Set brightness to value
• -G — Get brightness, default (if you run her with nothing, this is what you get)
• -N — Set minimum brightness to value
• -P — Get minimum brightness
• -O — Save current brightness 💾
• -I — Restore previously saved brightness ♻️

---

🦋 OPTIONS 🦋

and now, the glow-up options — the behavior of the above commands can be modified using these:

• -r — Interpret input and output values in raw mode 🧚
• -s PATH — Specify device target path. Use -L to list available devices (pick your fave, she's polyamorous with hardware)
• -v LEVEL — Set verbosity level. by default light only outputs read values, so here's the tier list:
  • 0: Read values
  • 1: Read values, Errors
  • 2: Read values, Errors, Warnings
  • 3: Read values, Errors, Warnings, Notices

---

🍓 FILES 🍓

the way she stores things depends on the mode, and this matters:

• When run in its classic SUID root mode, light caches settings and current brightness in /etc/light 🔥
• In its non-privileged mode of operation, the ~/.cache/light directory is used instead 🌸

bestie pls note: SUID root mode is the one that writes into /etc/light. non-privileged keeps it cozy in ~/.cache/light. two different addresses, two different vibes, don't mix them up 🙈

---

💜 AUTHORS 💜

Copyright © 2012-2018 Fredrik Haikarainen 💖

This is free software, see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE 💀

---

okay that's the whole page, and honestly? she ate. this dropped as LIGHT(1) on GNU/Linux, dated August 4, 2018, and that's your local-manual moment of the day. brightness controlled, keyboard glowing, no notes. periodt ✨🎀🫶