Batch Convert NRG files to ISO files on OS X

1.  Download PowerISO for OSX and save the executable (poweriso) in a folder in your PATH (e.g. /usr/local/bin or /usr/bin).
2. Open Terminal and go to the folder where NRG files are.
3. Execute the following:
   ls *.nrg | awk '{print("poweriso convert "$1" -o "$1" -ot iso")}' | sed 's/nrg/iso/2' | /bin/sh
4. Step 3 should work in most cases, but if the above produces a message saying
   The type of the source and destination image file is identical. No conversion is needed
   then we have to convert the NRG files in two steps:
5. Execute the following, which expands each NRG file into a folder of the same name: 
   ls *.nrg | awk '{print("poweriso extract "$1" / -od "$1)}' | sed 's/.nrg//2' | /bin/sh
6. Then execute the following, which creates an ISO file for each folder the above command created (and deletes the folder at the end): 
   ls -d */ | awk '{print("hdiutil makehybrid "$1" -o "$1); print("rm -fr "$1)}' | sed 's/\//.iso/2' | /bin/sh

For each command, you can do a test-run and print out what it will execute by running it without   | /bin/sh .