This is signals/ouch.c (Listing 20-1, page 399), an example from the book, The Linux Programming Interface.

The source code file is copyright 2022, Michael Kerrisk, and is licensed under the GNU General Public License, version 3.

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Function list (Bold in this list means a function is not static)

/* ouch.c

   Catch the SIGINT signal, generated by typing control-C (^C).

   Note that although we use signal() to establish the signal handler in this
   program, the use of sigaction() is always preferable for this task.
#include <signal.h>
#include "tlpi_hdr.h"
static void
sigHandler(int sig)
    printf("Ouch!\n");                  /* UNSAFE (see Section 21.1.2) */
main(int argc, char *argv[])
    int j;

    /* Establish handler for SIGINT. Here we use the simpler signal()
       API to establish a signal handler, but for the reasons described in
       Section 22.7 of TLPI, sigaction() is the (strongly) preferred API
       for this task. */

    if (signal(SIGINT, sigHandler) == SIG_ERR)

    /* Loop continuously waiting for signals to be delivered */

    for (j = 0; ; j++) {
        printf("%d\n", j);
        sleep(3);                       /* Loop slowly... */


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