1#define _GNU_SOURCE	/* needed to get the defines */
 2#include <fcntl.h>	/* in glibc 2.2 this has the needed
 3				   values defined */
 4#include <signal.h>
 5#include <stdio.h>
 6#include <unistd.h>
 7
 8static volatile int event_fd;
 9
10static void handler(int sig, siginfo_t *si, void *data)
11{
12	event_fd = si->si_fd;
13}
14
15int main(void)
16{
17	struct sigaction act;
18	int fd;
19
20	act.sa_sigaction = handler;
21	sigemptyset(&act.sa_mask);
22	act.sa_flags = SA_SIGINFO;
23	sigaction(SIGRTMIN + 1, &act, NULL);
24
25	fd = open(".", O_RDONLY);
26	fcntl(fd, F_SETSIG, SIGRTMIN + 1);
27	fcntl(fd, F_NOTIFY, DN_MODIFY|DN_CREATE|DN_MULTISHOT);
28	/* we will now be notified if any of the files
29	   in "." is modified or new files are created */
30	while (1) {
31		pause();
32		printf("Got event on fd=%d\n", event_fd);
33	}
34}

 1// SPDX-License-Identifier: GPL-2.0
 2#define _GNU_SOURCE	/* needed to get the defines */
 3#include <fcntl.h>	/* in glibc 2.2 this has the needed
 4				   values defined */
 5#include <signal.h>
 6#include <stdio.h>
 7#include <unistd.h>
 8
 9static volatile int event_fd;
10
11static void handler(int sig, siginfo_t *si, void *data)
12{
13	event_fd = si->si_fd;
14}
15
16int main(void)
17{
18	struct sigaction act;
19	int fd;
20
21	act.sa_sigaction = handler;
22	sigemptyset(&act.sa_mask);
23	act.sa_flags = SA_SIGINFO;
24	sigaction(SIGRTMIN + 1, &act, NULL);
25
26	fd = open(".", O_RDONLY);
27	fcntl(fd, F_SETSIG, SIGRTMIN + 1);
28	fcntl(fd, F_NOTIFY, DN_MODIFY|DN_CREATE|DN_MULTISHOT);
29	/* we will now be notified if any of the files
30	   in "." is modified or new files are created */
31	while (1) {
32		pause();
33		printf("Got event on fd=%d\n", event_fd);
34	}
35}