#!/bin/bash

PERC=`acpi | sed -nr "s/.*[^0-9]([0-9]{1,3})%.*/\1/p"`
LOWPOWER=20

if [ $PERC -lt $LOWPOWER ] 
  then
    echo -n "#[fg=red,bold]#[bg=black]! ~ "
fi

echo -n $PERC%


if [ $PERC -lt $LOWPOWER ] 
  then
    echo -n " ~ !#[fg=none]#[bg=none]"
fi