Convert disk IMG to standard ISO on a Macbook

This is not rocket science but born from a need to get something done in daily usage of a macbook and captured here for posterity.

With any luck this will help not only myself, but someone out there struggling with the same problems I encountered.

This will work for an IMG file or DMG.

I stumbled on the need for this after creating a DVD on my Macbook and wanting the generated IMG file to be in a standard ISO format.

Just use the command line:

// for IMG files.
$ hdiutil convert input.img -format UDTO -o output.iso

// for DMG files.
$ hdiutil convert input.dmg -format UDTO -o output.iso