pidfile_check() possible function

Pawel Jakub Dawidek pjd at
Tue Dec 20 06:10:46 PST 2005

On Tue, Dec 20, 2005 at 12:53:42PM +0300, Michael Bushkov wrote:
+> Hi!
+> I've just had a situation, where I want to know the pid of the already running daemon, but i don't want to create the pidfile in case if there is no daemon running. Such a 
+> situation can occur if the daemon has some kind of controlling program. This program should be able to know the pid of the daemon (to send a signal, or for some logging 
+> purposes).
+> With current pidfile API I don't see an appropriate way to do it. Pidfile_open() call can provide us with the PID. But if there is no daemon, this call will create the 
+> pidfile - and we'll have to use pidfile_remove() to do the cleanup. This behaviour doesn't seem to be appropriate.
+> Is it possible to introduce some function to return the pid of the already running daemon or (-1), for example, if no daemon exists. Possible syntax can be:
+> int pidfile_check(pid_t *pidptr);
+> What do you think about that?

Maybe... This function is not enough for sure, as you need to provide
file to look for pid at least.
Take a look at takepid() function in usr.bin/pkill/pkill.c to see how
pkill(1) is doing this.

Pawel Jakub Dawidek             
pjd at                 
FreeBSD committer                         Am I Evil? Yes, I Am!
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