This baffles me.
sudo [any command here ]
bash: sudo: command not found
Eek!
I tried to uninstall the Ruby Version Manager (it wouldn't compile Ruby for some reason). Somewhere in following their step-by-step instructions, I became sudo-less.
Here is my $PATH: /usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin
which sudo returns nothing.
I figured I'd try a shot-in-the-dark while I was waiting. I have an older Mac that I just upgraded to Lion two days ago. I copied its /usr/bin/sudo onto the problem machine. Now when I attempt to sudo, I get:
sudo: must be setuid root
I'm not particularly savvy with the command line — this seems bad.