SIGQUIT
Ctrl+\ — ends things like its sibling, but leaves a core dump as a keepsake.
The quit key was designed for the programmer, not the user: besides ending the foreground process, it dumps the memory image into a core file, ready for the autopsy in a debugger.
Today it is plan B for whoever watches Ctrl+C get swallowed by a stuck program: QUIT is rarely caught. On systemd systems, coredumpctl lists what the ring left behind.
$ ./servidor-preso
^\Quit (core dumped)
$ coredumpctl list --since=-5min
TIME PID SIG COREFILE EXE
qui 2026-08-07 14:02 -03 4242 SIGQUIT present servidor-preso