Ctrlz always works for me, to suspend the process and resume the shell terminal.
kill -9 <PID>
pkill -9 bar
usually does the trick.
[p]kill -9 sends the KILL signal to the process identified by Process ID, or executable name.
On an Ubuntu box, you can substitute <PID> for `jobs -p`, (with backticks), which just prints the process ID of other child processes of the current shell (hopefully only the process just suspended with Ctrlz).
On OSX, you have to type in the PID manually, or use
pkill. You can find other child jobs' PID's with
jobs -l (
jobs -p doesn't work on OSX), which prints other information as well as the PID.
In the case that Ctrlz doesn't work, open a new terminal window up and identify the process ID with
ps aux | grep bar
[p]kill as above.