Comment 25 for bug 280518

On Fri, Apr 10, 2009 at 08:55:02PM -0000, Jeremy LaCroix wrote:
> The contents of each of those files is "7". (If it makes any difference,
> I had the laptop plugged in to AC power which makes the brightness go up
> as high as it can during POST).

> The command that started with "echo 2" did nothing because I prefixed it
> with "sudo" and it still wouldn't let me edit it. I edited it with Kate
> and nothing changed, not sure if I have to log out after I change that
> file or not.

You'll need to edit the file by running:

  sudo -s
  echo 2 > /sys/devices/virtual/backlight/acpi_video0/brightness

(redirection happens in the parent shell, not as part of the sudo command,
so is not happening as root; editors are unlikely to work correctly on the
special files under /sys.)

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