SignalHelloWorld.c

#include <stdio.h>
#include <stdlib.h> // void exit( int exit_code)
#include <signal.h> // void (*signal( int sig, void (*handler) (int))) (int)

// handler must be of the form  "void func (int sig)"
// signal_code is useful in-cases where handler is used for more than one signal
void handler (int signal_code) 
{
    printf ("\nHello World!\n");
    printf ("signal value: %d\n", signal_code);
    exit (1);
}
int main (int argc, char *argv[])
{
    // register handler function to handle signal SIGINT = interrupt from
    // keyboard (^C)
    signal (SIGINT, handler);
    while (1)
        ; // Busy Wait until application receives SIGINT.

    // Never reached.
    return 0;
}