#include <stdio.h>     /* standard I/O functions                         */
#include <unistd.h>    /* standard unix functions, like getpid()         */
#include <signal.h>    /* signal name macros, and the signal() prototype */

/* first, here is the signal handler */
void catch_int(int sig_num)
{
    /* re-set the signal handler again to catch_int, for next time */
    signal(SIGINT, catch_int);
    printf("Don't do that\n");
    fflush(stdout);
}

int main(int argc, char* argv[])
{
    /* set the INT (Ctrl-C) signal handler to 'catch_int' */
    signal(SIGINT, catch_int);

    /* now, lets get into an infinite loop of doing nothing. */
    for ( ;; )
        pause();
}