Comment 70 for bug 935778

In the recent ubuntu 13.04 Beta 2, /sys/class/backlight/acpi_video0 did not exist anymore on my toshiba satellite Z930 (acpi_backlight=vendor is NOT set). Therefore I had to change the udev script proposed by @cmtsij like this:

diff --git a/etc/udev/rules.d/00-tosh-backlight.rules b/etc/udev/rules.d/00-tosh-backlight.rules
new file mode 100644
index 0000000..dd38aa2
--- /dev/null
+++ b/etc/udev/rules.d/00-tosh-backlight.rules
@@ -0,0 +1 @@
+DEVPATH=="*/toshiba", SUBSYSTEM=="backlight", ACTION=="change", RUN+="/etc/udev/rules.d/tosh-backlight.sh"
diff --git a/etc/udev/rules.d/tosh-backlight.sh b/etc/udev/rules.d/tosh-backlight.sh
new file mode 100755
index 0000000..c7dc5b2
--- /dev/null
+++ b/etc/udev/rules.d/tosh-backlight.sh
@@ -0,0 +1,7 @@
+#!/bin/sh
+
+acpi_max=$(cat /sys/class/backlight/toshiba/max_brightness)
+acpi_curr=$(cat /sys/class/backlight/toshiba/brightness)
+intel_max=$(cat /sys/class/backlight/intel_backlight/max_brightness)
+intel_curr=$(($intel_max*$acpi_curr/$acpi_max))
+echo $intel_curr > /sys/class/backlight/intel_backlight/brightness