Additional Topics > External Development Guide > IDLInternals - UNIX Signals > Signal Handlers

# Signal Handlers

IDL signal handler functions are defined as:

typedef void (* IDL_SignalHandler_t)(int signo);

When a signal is delivered to the process, all registered signal handlers are called. signo is the integer number of the signal delivered, as defined by the C language header file `signal.h` (found in `/usr/include/signal.h` on most UNIX systems).`signo` can be used by a signal handler registered for more than one signal to tell which signal called it.