Question

I encounter some problem when using inotify.
I use inotify to monitor changes on files. Here is my code:

int fd = inotify_init();
int wd = inotify_add_watch(fd, "/root/temp", IN_ALL_EVENTS);
int bufSize = 1000;
char *buf = new char[bufSize];
memset(buf, 0, sizeof(buf));
int nBytes = read(fd, buf, bufSize - 1);
cout << nBytes << " bytes read" << endl;
inotify_event *eventPtr = (inotify_event *)buf;
int offset = 0;
while (offset < nBytes)
{
    cout << eventPtr->mask << endl;
    offset += sizeof(inotify_event) + eventPtr->len;
    eventPtr = (inotify_event *)(buf + offset);
}
delete []buf;

If I delete “/root/temp” and re-create such a file, any changes to this file is not monitored by inotify, anyone how is this? Thanks.

cheng

Answer 1

That’s because inotify monitors the underlying inode, not the filename. When you delete that file, the inode you’re currently watching becomes invalid, therefore, you must invoke inotify_rm_watch. If you want to monitor a new file with the same name, but a different inode, you must detect when it’s created by monitoring its parent folder.