I was trying to debug an STunnel installation on my Raspberry Pi (using Raspbian) and so I set the foreground mode to yes (which is something suggested in the official documentation). Unfortunately, now every time the Raspberry Pi boots up, it will present the log to me in the foreground, with no way for me to run any other command, browse the file system, etc.
I tried Ctrl+Z, but that didn't work. The only thing that seems to work is Ctrl+Alt+Delete, but that just reboots the Raspberry Pi.