code:

# We should have some way here of keeping the car parked. What if
# they try to drive off while we're in the middle of an upgrade?

# We should also have a mutex around everything that follows. What if
# unpack.sh gets triggered on the same tarball twice? This is more of
# a problem now that we might be deferring installation.

# We should also have a recovery system. What if we remove the
# tarball filename but this process is killed before it can complete?