Inotify不适用于etc / passwd

Question

I am trying to set listner for passwd file in /etc directory and I am getting notification only for first password change.

fd = inotify_init();
wd = inotify_add_watch (fd, "/etc/passwd", IN_MODIFY);
while(1)
{
 read (fd, buff, BUFF_SIZE);
 struct inotify_event *event = ( struct inotify_event * ) &buff[ i ];
 printf("Event Len -  %d  wd %d \n", event->len, event->wd);
}

why it works first time and not later?I Am seeing timestamp change everytime when I change password. Same set of code working fine for some other file.

Answer 1

When changing the /etc/passwd , most application create a new file and rename it. This give a new inode number.