[G2 Q&A, Help & Troubleshooting] khaytsus:
Note, I'm on AOKP 4.3 with its kernel. These very well might not be exactly the same for all ROMs.

Attaching a script, it's just for playing, not really very useful at this point. Your device must be awake for the script to run properly, otherwise you'll find "sleep 1" (sleep 1 second) taking 5-10 seconds ;)

If the devices in the script don't exist to play with, try find /sys | grep brightness to find them on your ROM.

green() etc turn it on the first time you hit the function, turn it off the next. The rear LEDs were a little weird, so I did them differently. They always show as 71 for some reason, where the others show 0 when they're off. Anyway, it works. I'm not checking any arguments, but some expect a second argument, and the third argument isn't used at all. Anyway, just an example, nothing you can directly use.

#!/bin/sh

rear_left="/sys/devices/leds-qpnp-d8117600/leds/button-backlight1/brightness"
rear_left_max="/sys/devices/leds-qpnp-d8117600/leds/button-backlight1/max_brightness"
rear_right="/sys/devices/leds-qpnp-d8117600/leds/button-backlight2/brightness"
rear_right_max="/sys/devices/leds-qpnp-d8117600/leds/button-backlight2/max_brightness"
red="/sys/devices/leds-qpnp-d8117200/leds/red/brightness"
red_max="/sys/devices/leds-qpnp-d8117200/leds/red/max_brightness"
blue="/sys/devices/leds-qpnp-d8117200/leds/blue/brightness"
blue_max="/sys/devices/leds-qpnp-d8117200/leds/blue/max_brightness"
green="/sys/devices/leds-qpnp-d8117200/leds/green/brightness"
green_max="/sys/devices/leds-qpnp-d8117200/leds/green/max_brightness"
torch="/sys/devices/leds-qpnp-d8117400/leds/led:flash_torch/brightness"
torch_max="/sys/devices/leds-qpnp-d8117400/leds/led:flash_torch/max_brightness"

# These could be useful for blink/rgb but not working from what I've found
# so far, but good info from the Tasker forum
# https://groups.google.com/forum/#!topic/tasker/pKWOQXZv7Hs/discussion
blink_patterns="/sys/devices/virtual/g2_rgb_led/use_patterns/blink_patterns"
input_patterns="/sys/devices/virtual/g2_rgb_led/use_patterns/input_patterns"
onoff_patterns="/sys/devices/virtual/g2_rgb_led/use_patterns/onoff_patterns"

pattern=$1
time_on=$2
time_off=$3

green()
{
echo "green"
if [ `cat $green_max` == `cat $green` ]; then
echo 0 > $green
else
echo `cat $green_max` > $green
fi
}

red()
{
echo "red"
if [ `cat $red_max` == `cat $red` ]; then
echo 0 > $red
else
echo `cat $red_max` > $red
fi
}

blue()
{
echo "blue"
if [ `cat $blue_max` == `cat $blue` ]; then
echo 0 > $blue
else
echo `cat $blue_max` > $blue
fi
}

rear_left()
{
if [ `cat $rear_left` -gt 0 ]; then
echo 0 > $rear_left
else
echo `cat $rear_left_max` > $rear_left
fi
}

rear_right()
{
if [ `cat $rear_right` -gt 0 ]; then
echo 0 > $rear_right
else
echo `cat $rear_right_max` > $rear_right
fi
}

torch()
{
if [ `cat $torch_max` == `cat $torch` ]; then
echo 0 > $torch
else
echo `cat $torch_max` > $torch
fi
}

flashtorch()
{
flashes=0
while [ $flashes -lt $time_on ]; do
let flashes=flashes+1
torch
usleep 50000
torch
usleep 40000
done
}

case $pattern in
testrear)
rear_left
sleep $time_on
rear_left
sleep $time_on
rear_right
sleep $time_on
rear_right
sleep $time_on
rear_left
rear_right
sleep $time_on
rear_left
rear_right
;;
testfront)
green
sleep 1
green
blue
sleep 1
blue
red
sleep 1
red
;;
testwhite)
red
green
blue
sleep 1
red
green
blue
;;
flashtorch)
flashtorch
;;
esac