In an interactive console like
irb, sometimes something will go wrong and the console becomes unresponsive. One solution is to suspend the process, then kill it.
To suspend the process, I can press
Control+Z. To kill that process, I can run
ps -ef | grep 'irb' to list all the processes and show only the ones that contain 'irb', then get the process ID from that list and type
kill [insert PID here].
That's a hassle. I know that there's a way to just suspend the process, then type
kill [some symbol here], with the symbol representing "the last process that was suspended."
What's the command-line symbol for "the PID of the last suspended process"?