shaw@hpihoah.HP.COM (Joy-lim Shaw) (02/02/90)
/ hpihoah:comp.unix.questions / rli@buster.irby.com (Buster Irby) / 8:08 pm Jan 27, 1990 / >ric@ace.sri.com (Richard Steinberger) writes: >>Sometimes I see a user has been logged on several days without doing >>anything. ps shows that the process is sleeping, waiting for input. >>Many times I am unable to kill such a process. What I have been doing >>is kill -9 PID, where PID is the user's process ID. Could someone >>shed some light on why such processes don't die. Is there a particular >>document that I might peruse to understand this situation better? And >>if kill -9 doesn't work, do I have any alternatives other than reboot? How these software signals work, is that periodically a function that checks the signal queue is run on your behalf. This is done, among other time, when a process switches mode (User mode to Kernal mode, and visa versa). So when a process is waiting for a driver, and the driver is waiting for a hardware signal, it never checks the signal queue until it returns from the driver. In short, that process is just not listening to your signals. To kill this process, one usually has to reboot the machine, but if you know that this process is waiting for a signal for say a tape drive. Try putting the tape drive back on line or some other things to get the tape drive to generate a hardware signal. Any signal will do as the driver is probably listening for anything. But usually you'll have to reboot to kill that process. Of course if the process isn't causing any problems other then being there, why reboot? Let it sit there until you can reboot at a more opertune (sp) time or its next scheduled down time. For more information you can try looking it up in a UNIX kernal book. The Bach book must have it. And for more information as to when the signal queue is checked, you'll have to check with the folks who wrote your kernal. Hope this helps. shaw
nigel@cmsfl@labtam.oz (Nigel Harwood) (02/15/90)
First of I'm not a guru on this but I have picked up a couple of things along the way ... In article <8498@unix.SRI.COM>, ric@ace.sri.com (Richard Steinberger) writes: > Sometimes I see a user has been logged on several days without doing > anything. ps shows that the process is sleeping, waiting for input. You should try kill -1 PID first. This is much nicer to the user i.e. if he/she is in say vi and it gets a -1 signal it will save the edit session for them. A -9 will just clobber the process. > Many times I am unable to kill such a process. What I have been doing > is kill -9 PID, where PID is the user's process ID. Could someone > shed some light on why such processes don't die. The ones I have struck which can't be killed I have assumed to be what are called zombie processes. Processes whose parent i.e. the shell or something, have died and they have not for what ever reason. Perhaps someone with real knowledge can fill that one in ;-) > Is there a particular > document that I might peruse to understand this situation better? And > if kill -9 doesn't work, do I have any alternatives other than reboot? I have had to reboot as well. > thanks to all who reply. Apologies if this is frequently dealt with. Never seen it before in comp.sys.ncr but probably has been beaten to death in comp.unix.questions etc. -- <<<<<<<<<<<<<<<<<<<<<<< Nigel Harwood >>>>>>>>>>>>>>>>>>>>>>>>> << Post: Coles Myer Ltd, PO Box 2000 Tooronga 3146, Australia >> << Phone: +61 3 829 6090 E-mail: nigel%cmsfl@labtam.oz.au >> <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>