So why the need for both files though... The file dosen't have to be empty to be used as a lock... Why not just create a pid file and check that instead of having one file to just hold the pid and another file just to lock -- I'm just trying to determine if there is a specific reason or it just has developed that way. Also just to be clear -- the application is responsable for creating the pid file right?
Thank you! On 6/27/05, Michael Gale <[EMAIL PROTECTED]> wrote: > Hello, > > If a process exits normally the PID file will be removed, you are > making the kernel kill the process by using `kill -9`. > > You should not be using kill -9 as a norm. You should shutdown the > application according to the documentation provided with the app. > > If there is no specify way then a standard `kill` command should do not > the trick. > > If PID files are left behind usually this is because the process was > shutdown correctly. This is not a problem, most applications will just > over write the PID file the next time they start up. > > How ever some apps will complain and then you would be required to > remove the PID file. > > If you pay closer attention to the files in /var/run and > /var/lock/subsys you will notice that all the files in /var/run/ are > about 5k and contain a number, which is the PID. > > The files located in /var/lock/subsys will be empty :) because there are > there as place holders / locks so to speak. When an application is > running it can us this directory as for file locking. For example If I > ran passwd and it needed to lock the file until I was done (which it > does not) then it would touch a file called passwd in /var/lock/subsys > and if another user tried to run passwd it would not let me make changes > because the lock file exist. > > Michael > > > > Stephen Cartwright wrote: > > But why are the files in /var/lock/subsys on RH and (RH based distros) > > created given that there is already pid files in /var/run/ which can > > be used to tell whether or not daemon is already running. The lock > > files in /var/lock/subsys don't seem to lock a resource, they just > > seem to indicate that the process is running... but then why not just > > use the pid file? > > > > Also what happens if the process dies unexpectedly? How does it work > > with pid files? Is the creation and removal of the pid file done by > > the OS? Is /var/run checked for old pid files? I used "kill -9" to > > kill a process and the pid file was still there. > > > > Thank you! > > > > On 6/27/05, Robert Lewko <[EMAIL PROTECTED]> wrote: > > > >>On June 27, 2005 10:47 am, Stephen Cartwright wrote: > >> > >>>What exactly is the difference between a pid file and a subsystem lock > >>>file? Why do you need both of them? > >>> > >>>Thanks! > >> > >>A *.pid file is a file that keeps the PID "process id" and that is to record > >>which process to send signals to for various reasons, ie. killing the > >>process > >>(thats not the only reason, but the most common one). > >> > >>What a lock file is for is to signal that a particular resource is in use > _______________________________________________ clug-talk mailing list [email protected] http://clug.ca/mailman/listinfo/clug-talk_clug.ca Mailing List Guidelines (http://clug.ca/ml_guidelines.php) **Please remove these lines when replying
