I would like to disable startup from one of my external USB drives. This is what appears in my Refit config file. What exactly do I have to change in order for my Mac to either boot from my Linux or internal Mac partition? Both partitions reside on my internal iMac drive.
# Disable menu options for increased security. These are intended for a lab
# environment where the administrator doesn't want users to mess with the
# operating system. List the names for the options you want to hide from
# the boot menu. Currently supported:
# shell - remove the EFI shell
# tools - remove all EFI tools (shell and gptsync)
# optical - no booting from optical drives
# external - no booting from external disks or USB flash drives
# internal - no booting from internal disks; this setting is not
# recommended because it locks you out of all operating
# systems installed on the internal hard disks.
# singleuser - remove the submenu options to boot Mac OS X in single-user
# or verbose modes
# hwtest - remove the submenu option to run Apple Hardware Test
# all - all of the above, except for 'internal'
#disable external optical shell singleuser