Initial Fedora brightness automation setup

bin/brightness-sync-hg342pcb

@@ -0,0 +1,65 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+CONFIG="${BRIGHTNESS_AUTOMATION_CONFIG:-$HOME/.config/brightness-automation/env}"
+if [[ -f "$CONFIG" ]]; then
+  # shellcheck disable=SC1090
+  source "$CONFIG"
+fi
+
+MODEL="${BRIGHTNESS_DDCUTIL_MODEL:-HG342PCB}"
+DISPLAY_NUM="${BRIGHTNESS_DDCUTIL_DISPLAY:-1}"
+BUS_NUM="${BRIGHTNESS_DDCUTIL_BUS:-16}"
+BACKLIGHT_PATH="${BRIGHTNESS_SYNC_BACKLIGHT:-/sys/class/backlight/intel_backlight}"
+INTERVAL="${BRIGHTNESS_SYNC_INTERVAL:-1}"
+MIN_PERCENT="${BRIGHTNESS_SYNC_MIN_PERCENT:-1}"
+
+brightness_percent() {
+  local current max percent
+
+  current="$(<"${BACKLIGHT_PATH}/brightness")"
+  max="$(<"${BACKLIGHT_PATH}/max_brightness")"
+  percent="$(( (current * 100 + max / 2) / max ))"
+
+  if (( percent < MIN_PERCENT )); then
+    percent="$MIN_PERCENT"
+  elif (( percent > 100 )); then
+    percent=100
+  fi
+
+  printf '%s\n' "$percent"
+}
+
+run_ddcutil() {
+  if sudo -n ddcutil --bus "$BUS_NUM" getvcp 10 >/dev/null 2>&1; then
+    sudo -n ddcutil --bus "$BUS_NUM" "$@"
+    return
+  fi
+
+  if sudo -n ddcutil --display "$DISPLAY_NUM" getvcp 10 >/dev/null 2>&1; then
+    sudo -n ddcutil --display "$DISPLAY_NUM" "$@"
+    return
+  fi
+
+  if sudo -n ddcutil --model "$MODEL" getvcp 10 >/dev/null 2>&1; then
+    sudo -n ddcutil --model "$MODEL" "$@"
+    return
+  fi
+
+  echo "External ${MODEL} was not reachable via sudo -n ddcutil." >&2
+  return 1
+}
+
+last_percent=""
+
+while true; do
+  percent="$(brightness_percent)"
+
+  if [[ "$percent" != "$last_percent" ]]; then
+    if run_ddcutil setvcp 10 "$percent" >/dev/null; then
+      last_percent="$percent"
+    fi
+  fi
+
+  sleep "$INTERVAL"
+done