Setting brightness Ubuntu

I have a problem about the brightness in Ubuntu, when I restart my Ubuntu. The brighness back to 100% value. I found the solution edit the rc.local file, that file is running when Ubuntu starting.

To know the value bringhtness:
$ cat /sys/class/backlight/acpi_video0/brightness
$ cat /sys/class/backlight/intel_backlight/brightness 

Add command into rc.local file
$ sudo gedit /etc/rc.local

Add the command above exit 0 for acpi_video0/brighness, i try setting intel_backlight/brightness but not working, so i setting the acpi_video0/brightness.

echo X > /sys/class/backlight/acpi_video0/brightness

The X is value the brightness what you want.

My rc.local

I hope this can help