38.15 Cleaning Up an Unkillable Process

You or another user might have a process that (according to ps (38.5)) has been sleeping for several days, waiting for input. If you can't kill (38.10) the process, even with kill -9, there may be a bug or some other problem.

• These processes can be unkillable because they've made a request for a hardware device or network resource. UNIX has put them to sleep at a very high priority and the event that they are waiting on hasn't happened (because of a network problem, for example). This causes all other signals to be held until the hardware event occurs. The signal sent by kill doesn't do any good.

• If the problem is with a terminal and you can get to the back of the terminal or the back of the computer, try unplugging the line from the port. Also, try typing CTRL-q on the keyboard - if the user typed CTRL-s while getting a lot of output, this may free the process.

• Ask your vendor if there's a special command to reset the device driver (42.1). If there isn't, you may have to reboot the computer.