Real ros root
ROS_ROOT doesn't point to the root of a ros installation (i.e. where setup.sh, the base binaries, base libs reside), but I'm looking for installation root for use with a release script I'm writing.
Is there a way to figure this out programmatically? I know for example in fuerte I could simply figure out what the relative path is and adjust, but it's different for previous versions, and I'd like to use a sanctioned way to avoid edge cases/be future-proof.