example/posix/processes-sigint.c

Shows how to install a custom signal handler

#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>

// A function that gets called if it is
// installed as a handler for a signal and
// that signal is recieved by the process
void handle_SIGINT(int)
{
    printf("Received the INT signal\n");
}

int main(int argc, const char* argv[])
{
    printf("Installing handler for the INT signal\n");
    // install our handler for the SIGINT signal
    // and remember the previous handler (the default)
    // SIGINT is sent to the process running on a terminal
    // when Ctrl+C is pressed
    sighandler_t old_handler = signal(SIGINT, handle_SIGINT);

    // wait 10 seconds
    // with the handler installed pressing Ctrl+C will cause
    // the message to be printed but the process will not exit
    for(int i=0; i!=10; ++i)
    {
        printf("%d\n", i);
        sleep(1);
    }

    printf("Restoring the default handler\n");
    // install the previous signal handler
    signal(SIGINT, old_handler);

    // wait again
    // with the default handler when Ctrl+C is pressed
    // the process will exit
    for(int i=0; i!=10; ++i)
    {
        printf("%d\n", i);
        sleep(1);
    }

    return 0;
}