The following signals can be handled by Factor programs:
SIGWINCH
SIGCONT
SIGURG
SIGIO
SIGPROF
SIGALRM
SIGVTALRM
SIGINFO (if available on the host platform)
SIGUSR1

Synchronous signals such as SIGILL, SIGFPE, SIGBUS, and SIGSEGV are handled by the Factor implementation and reported as exceptions when appropriate. SIGUSR2 is used by Factor internally. SIGINT and SIGQUIT are used by Factor to pause the VM and enter into the low-level debugger (like the die word); they cannot yet be handled reliably by Factor code.