Wollte nun deine Methode ausprobieren. Leider funktioniert sie nicht. Udev beklagt fehlende write permissions:
rules contain 196608 bytes tokens (16384 * 12 bytes), 29071 bytes strings
16404 strings (148211 bytes), 13925 de-duplicated (121620 bytes), 2480 trie nodes used
PROGRAM '/usr/local/bin/udevbacklight.sh' /etc/udev/rules.d/50-powersave.rules:1
starting '/usr/local/bin/udevbacklight.sh'
'/usr/local/bin/udevbacklight.sh' [4742] exit with return code 0
ATTR '/sys/devices/pci0000:00/0000:00:02.0/backlight/acpi_video0/brightness' writing '12' /etc/udev/rules.d/50-powersave.rules:1
error opening ATTR{/sys/devices/pci0000:00/0000:00:02.0/backlight/acpi_video0/brightness} for writing: Permission denied
ACTION=add
DEVPATH=/devices/pci0000:00/0000:00:02.0/backlight/acpi_video0
SUBSYSTEM=backlight
USEC_INITIALIZED=1014635160
unload module index
Manuell kann ich jedoch schreiben:
[root@thinkpad acpi_video0]# echo 12 > /sys/devices/pci0000\:00/0000\:00\:02.0/backlight/acpi_video0/brightness
Habe deine Regel an mein System angepasst:
[orschiro@thinkpad ~]$ cat /etc/udev/rules.d/50-powersave.rules
ACTION=="add", DEVPATH=="/devices/pci0000:00/0000:00:02.0/backlight/acpi_video0", SUBSYSTEM=="backlight", SUBSYSTEMS=="pci", DRIVERS=="i915", PROGRAM="/usr/local/bin/udevbacklight.sh", ATTR{brightness}="%c{1}"
Eine Idee, warum Udev nicht mit Schreibrechten schreiben kann?
Zum Schluss noch der Output von udevadm:
[orschiro@thinkpad acpi_video0]$ udevadm info -a -p /sys/class/backlight/acpi_video0
Udevadm info starts with the device specified by the devpath and then
walks up the chain of parent devices. It prints for every device
found, all possible attributes in the udev rules key format.
A rule to match, can be composed by the attributes of the device
and the attributes from one single parent device.
looking at device '/devices/pci0000:00/0000:00:02.0/backlight/acpi_video0':
KERNEL=="acpi_video0"
SUBSYSTEM=="backlight"
DRIVER==""
ATTR{type}=="firmware"
ATTR{brightness}=="12"
ATTR{bl_power}=="0"
ATTR{max_brightness}=="15"
ATTR{actual_brightness}=="12"
looking at parent device '/devices/pci0000:00/0000:00:02.0':
KERNELS=="0000:00:02.0"
SUBSYSTEMS=="pci"
DRIVERS=="i915"
ATTRS{irq}=="48"
ATTRS{subsystem_vendor}=="0x17aa"
ATTRS{broken_parity_status}=="0"
ATTRS{class}=="0x030000"
ATTRS{consistent_dma_mask_bits}=="36"
ATTRS{dma_mask_bits}=="36"
ATTRS{local_cpus}=="00000000,00000003"
ATTRS{device}=="0x2a42"
ATTRS{msi_bus}==""
ATTRS{local_cpulist}=="0-1"
ATTRS{vendor}=="0x8086"
ATTRS{subsystem_device}=="0x20e4"
ATTRS{boot_vga}=="1"
ATTRS{numa_node}=="-1"
ATTRS{d3cold_allowed}=="1"
looking at parent device '/devices/pci0000:00':
KERNELS=="pci0000:00"
SUBSYSTEMS==""
DRIVERS==""