Hi, for the OpenBSD version, see kevent(2) and grep the source for kevent, kqueue, and EV_SET.
BSD 4.4 used select(2) because it was faster than sleep (you can find the sources e.g. on github). Best regards Robert On Fri, 17 Feb 2023 08:23:13 +0300 Maksim Rodin <a23s4a2...@yandex.ru> wrote: > Hello, > Sorry if I chose the wrong place to ask such a question. > I have been learning C for a couple of months and along with reading > "C Primer Plus" by Stephen Prata and doing some exercises from it I > took a hard (for me) task to replicate a tail program in its simplest > form. I was able to reproduce watching for new data and truncation of > the file using kqueue but I do not quite understand how the original > tail watches when the file appears again after deletion or renaming. > By reading the original tail sources downloaded from OpenBSD mirror I > see that this is done by calling tfreopen function which seems to use > a "for" loop to (continuously?) stat(2) the file name till stat(2) > successfully returns and it does not seem to load a CPU as a simple > continuous "for" loop would do. > Can someone explain how it is done? > May be there is a better way to watch for the file to appear > correctly? Is inserting a sleep(3) in a loop an appropriate way?
