Determining if a Mac is a laptop in a shell script

I needed a quick way to determine if the machine I was running a shell script on was a laptop or a desktop Mac. (The script I was working on is used to create a unique hostname for the machine automatically, and the machine type is part of that hostname)

It occurred to me that I could easily determine if the script were executing on a laptop by detecting the presence of a battery. I know that some basic battery information can be pulled from ioreg -w0 -l and that the same command returns nothing on Macs without a battery, so all I had to do what see if something came back from that command.

The code looks something like this:

 #!/bin/bash  
 type=`ioreg -w0 -l | grep Capacity`  
   
 if [ -z "$type" ]; then  
  type='Desktop'  
 else  
  type='Laptop'  
 fi  
   
 echo $type  

This seems to work well in Snow Leopard (10.6) and Lion (10.7).