Add inotify example

src/main.c

@@ -1,11 +1,69 @@
+/*This is the sample program to notify us for the file creation and file deletion takes place in “/tmp” directory*/
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/inotify.h>
 
-int main(int argc, char **argv)
+#define EVENT_SIZE (sizeof(struct inotify_event))
+#define EVENT_BUF_LEN (1024 * (EVENT_SIZE + 16))
+
+int main()
 {
-	printf("Hello systemd world \n");
-	fflush(NULL);
-	sleep(5);
-	return (EXIT_SUCCESS);
+	int length, i = 0;
+	int fd;
+	int wd;
+	char buffer[EVENT_BUF_LEN];
+
+	/*creating the INOTIFY instance*/
+	fd = inotify_init();
+
+	/*checking for error*/
+	if (fd < 0) {
+		perror("inotify_init");
+	}
+
+	/*adding the “/tmp” directory into watch list. Here, the suggestion is to validate the existence of the directory before adding into monitoring list.*/
+	wd = inotify_add_watch(fd, "/tmp", IN_CREATE | IN_DELETE);
+
+	/*read to determine the event change happens on “/tmp” directory. Actually this read blocks until the change event occurs*/
+
+	length = read(fd, buffer, EVENT_BUF_LEN);
+
+	/*checking for error*/
+	if (length < 0) {
+		perror("read");
+	}
+
+	/*actually read return the list of change events happens. Here, read the change event one by one and process it accordingly.*/
+	while (i < length) {
+		struct inotify_event *event =
+			(struct inotify_event *)&buffer[i];
+		if (event->len) {
+			if (event->mask & IN_CREATE) {
+				if (event->mask & IN_ISDIR) {
+					printf("New directory %s created.\n",
+					       event->name);
+				} else {
+					printf("New file %s created.\n",
+					       event->name);
+				}
+			} else if (event->mask & IN_DELETE) {
+				if (event->mask & IN_ISDIR) {
+					printf("Directory %s deleted.\n",
+					       event->name);
+				} else {
+					printf("File %s deleted.\n",
+					       event->name);
+				}
+			}
+		}
+		i += EVENT_SIZE + event->len;
+	}
+	/*removing the “/tmp” directory from the watch list.*/
+	inotify_rm_watch(fd, wd);
+
+	/*closing the INOTIFY instance*/
+	close(fd);
 }