Check OS X's Installer Log for installation issues
November 7th, 2007 by admin
A common problem with the IRAF installers is that / is sometimes not writeable by the admin group, and thus the “iraf user” can’t write files to the root of the hard drive. To see what goes wrong with the installer, please check the installer log. You can see a screenshot here.
If it’s something about permissions, making / writeable by the admin will probably fix it (assuming IRAF is an admin user, as I suggest)
sudo chmod g+w /
