Bash Script Issues (If statement for file copying)

Shell Programming and Scripting
1

Writing a bash script for use with Geektool, pulls the battery info, and shuffles images around so that an Image geeklet can display the correct expression as the desktop background. (Eventually I intend to make it more intricate, based on more variables, and add more expressions)

I'm extremely new to the language, but the script below did return a result the first time I ran it through Geektool. The only problem is that the variable did not match the result (batt at 95%, result was for 5% and below). It stopped working after that.

The percentage display works every time, but that's most likely because I didn't write that part of the script, I scavenged it. I'd rather use a variable than rerun the calculation over and over, but I couldn't get it to work.

#!/bin/bash

asbreg=`ioreg -rc "AppleSmartBattery"`

maxcap=`echo "${asbreg}" | awk '/MaxCapacity/{print $3}'`;
curcap=`echo "${asbreg}" | awk '/CurrentCapacity/{print $3}'`;

prcnt=`echo "scale=2; 100*$curcap/$maxcap" | bc`;

if [ 100*$curcap/$maxcap -gt 15 ] ; then

cp /Users/User/Desktop/Faces/Happy.png /Users/User/Desktop/Faces/Current/Current.png

elif [ 100*$curcap/$maxcap -gt 10 ] ; then

	cp /Users/User/Desktop/Faces/Queasy.png /Users/User/Desktop/Faces/	Current/Current.png

	elif [ 100*$curcap/$maxcap -gt 5 ] ; then

		cp /Users/User/Desktop/Faces/Angry.png /Users/User/Desktop/Faces/Current/Current.png

		elif [ 100*$curcap/$maxcap -gt 1 ] ; then 

			cp /Users/User/Desktop/Faces/Unconcious.png /Users/User/Desktop/Faces/Current/Current.png

fi

printf "%1.0f%%" ${prcnt};


#EOF
2

In bash you need to pre-evaluate mathematical expressions. eg.

if [ $(( 100 * $curcap / $maxcap )) -gt 15 ] ; then