monitor_dir_inotify.c

#include <errno.h>
#include <linux/inotify.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>

#define EVENT_SIZE (sizeof(struct inotify_event))
#define EVENT_BUF_LEN (1024 * (EVENT_SIZE + 16))

int main() {
  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);
}