compiz is the window manager used by Unity. Running
compiz --replace when Unity is running will start a new instance of the window manager, replacing the old instance.
Lubuntu uses the
openbox window manager. So if you want to do is to run a new instance of
openbox, replacing the old one, run:
That's probably what you want.
On the other hand, if you want to replace
compiz, just run
compiz --replace. (If that doesn't work, try killing
openbox manually first with
By the way, you've written
compiz --replace with a
# character in front of it, as though you're running it from a root shell. That would be wrong.
openbox, and other window managers should be run as the non-root user who is graphically logged in, not as root. Do not use
sudo to run