PowerTop - Howto Enable Device Power Management by pressing the P key

Have you ever ran powertop? If not, have a look at these links.

http://www.linuxpowertop.org/ 

http://www.lesswatts.org/index.php 

When you run powertop as root (eg. sudo powertop), it might recommend something like this: 

Enable Device Power Management by pressing the P key

So how do you do this when powertop is not running?

This forum made a suggestion that I have attempted to simplify.

find /sys/devices/pci* -path "*power/control" -exec bash -c "echo auto > '{}'" \;

Or you can use this slightly longer one that echo's values before and after it changes.

find /sys/devices/pci* -path "*power/control" -exec \
  bash -c "echo -n '{}' = && cat '{}' && echo auto > '{}' && echo -n '{}' = && cat '{}'" \;

Both have to be run as root or using sudo.

eg.

sudo find /sys/devices/pci* -path "*power/control" -exec bash -c "echo auto > '{}'" \; 

Here is my bash script that I run with an extra powertop recommendation that may 

not be applicable in your case.

#!/bin/bash

find /sys/devices/pci* -path "*power/control" -exec \
  bash -c "echo -n '{}' = && cat '{}' && echo auto > '{}' && echo -n '{}' = && cat '{}'" \;

F="/sys/module/snd_hda_intel/parameters/power_save"
echo -n $F = && cat $F
echo 1 > $F
echo -n $F = && cat $F