I'd like to simplify my GRUB menu so it has only the installed OS's list. (In my case, the Windows that came with the machine, Ubuntu 12.10, and CentOS 6.) I see no options in /etc/default/grub that disable this. I thought it was GRUB_DISABLE_RECOVERY but that's not it.
Is there a "clean" way to do this?
You can uninstall all the older kernels from Ubuntu, and the "Advanced Options" for Ubuntu should go away at least. Possibly the same for CentOS. I don't think I've ever seen an "Advanced Options for Windows" selection.
Also, if you've got CentOS and Ubuntu both installed to disk, then there is chance they will fight over the grub install to the MBR (or wherever your grub is installed to), as well.