What makes a volume bootable?
 

I have an Intel MacBook Pro and did something bad. I ran fdisk in Linux and removed the partition (an honest mistake, stop laughing!). In the past I've gotten the data back by putting the partitions back and then remounting (without formatting). So I recreated the single partition of type 'ee.' Now the data is there but it won't boot.

The drive shows up under "Startup Disk" in the preference pane, but not when I boot with the option key held down. Either way it won't boot. I superDuped it to my backup USB drive and now this boots, all my data is there, but it's on my external USB drive. I could superDupe it back, but it's over 100GB and I would rather not. In looking at the partitions with gpt show they look exactly the same.

Looking around the net I cannot find a way to manually make a bootable partition for the mac. Everyone says "copy a working partition." Any suggestions?

try the bless command
 

If you are comfortable with shell commands in Terminal, check out the bless command (man bless for details). From what I can tell, it is the normal way to make a partition bootable (I wouldd bet SuperDuper! uses it to make copied volumes bootable).

N.B. This is not something I have played with, just something I have read about.

Thanks for the suggestion. I hadn't tried that yet. After trying about every incarnation of that command everything is still the same (shows in Preferences>Startup Disk, but not on the option menu on boot). When I do try and boot off it, it sits around for awhile then gives the folder with a '?'

Guess I'll just SuperDupe it back tonight.

I think SuperDupering it back is a good idea.. unless Linux messed up the partition format!

That looks to have been the case. I Duped it back and it still didn't work. So I repartitioned it and Duped it back again, then it worked.