signals/intquit.c

This is signals/intquit.c (Listing 20-2, page 401), 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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/* intquit.c

   Catch the SIGINT and SIGQUIT signals, which are normally generated
   by the control-C (^C) and control-\ (^\) keys respectively.

   Note that although we use signal() to establish signal handlers 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)
{
    static int count = 0;

    /* UNSAFE: This handler uses non-async-signal-safe functions
       (printf(), exit(); see Section 21.1.2) */

    if (sig == SIGINT) {
        count++;
        printf("Caught SIGINT (%d)\n", count);
        return;                 /* Resume execution at point of interruption */
    }

    /* Must be SIGQUIT - print a message and terminate the process */

    printf("Caught SIGQUIT - that's all folks!\n");
    exit(EXIT_SUCCESS);
}
int
main(int argc, char *argv[])
{
    /* Establish same handler for SIGINT and SIGQUIT. 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)
        errExit("signal");
    if (signal(SIGQUIT, sigHandler) == SIG_ERR)
        errExit("signal");

    for (;;)                    /* Loop forever, waiting for signals */
        pause();                /* Block until a signal is caught */
}

 

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