This was tested on bash 4.3.22 (HP-UX) and bash 4.2.37 (Linux). Create a script named foo with the following content:
#!/bin/bash set -m while sleep 1; do :; done Make it executable, and type ./foo & at an interactive shell. You get your shell prompt back. You can press Enter as many times as you like. But if you press any key other than Enter, the entire terminal window goes away. Wrapping a few shells around it only postpones the inevitable. If you run a few nested "bash" shells as padding, and then run ./foo & in the innermost one, each non-Enter keystroke will kill one instance of bash, printing the word "exit" on the terminal. When all the shells die, so does the terminal. wooledg@wooledg:~$ bash wooledg@wooledg:~$ bash wooledg@wooledg:~$ bash wooledg@wooledg:~$ bash wooledg@wooledg:~$ ./foo & [1] 11945 wooledg@wooledg:~$ aexit wooledg@wooledg:~$ bexit wooledg@wooledg:~$ cexit wooledg@wooledg:~$ dexit wooledg@wooledg:~$ (The next keystroke after that removes the terminal.)
