Linux iNotify one shot and event mask problem

Question

I'm trying to use iNotify in linux rhel5, kernel 2.6.18, glibc 2.5-18. I did not define the event as one shot but for some some reason it behaves as if I did. The impact is that I have to re-add a watch after each event. Any one ever used iNotify? Another problem is that the mask returned in the event object contains only one flag: IN_ONE_SHOT.

Answer 1

It is probable that inotify is implicitly deleting the watch because the file is being deleted. The behaviour is subtly referred to by the manual page (see the section on the IN_IGNORED event). You can check if this is happening by checking if the flag IN_IGNORED is set in the inotify_event populated by your call to read .

See also inotify delete_self when modifying and saving a file for why the file may be deleted without your knowledge or action during what you think is just a modification.

Answer 2

Write the smallest example you can and test that. If it demonstrates the behaviour you are talking about then add it to your question. If it behaves normally then add a little more of your code and test again. Keep repeating until you have reproduced the error or you have your code working. Often I find that building a toy program tells me exactly what I am doing wrong that I could not see in a larger program.