How to kill a daemon with its name gracefully

killprocess

I usually kill a process with killall.

killall markdoc

But I am not sure if this command terminates the process gracefully.
Does this command achieve graceful termination? If it does not, how can I kill a process with its name gracefully?

Best Answer

Your question is not clear, you talk about a daemon in the title, but in the body only talk about a generic process.

For a daemon there are specific means to stop it, for example in Debian you have

    service daemon-name stop

    /etc/init.d/daemon-name stop

Similar syntaxes exist for other initscript standards used in other distributions/OS.

To kill a non-daemon process, supposing it is in some way out of control, you can safely use killall or pkill, given that they use by default the SIGTERM (15) signal, and any decently written application should catch and gracefully exit on receiving this signal. Take into account that these utilities could kill more that one process, if there are many with the same name.

If that do not work, you can try SIGINT (2), then SIGHUP (1), and as a last resort SIGKILL (9). This last signal cannot be catched by the application, so that it cannot perform any clean-up. For this reason it should be avoided every time you can.

Both pkill and killall accept a signal parameter in the form -NAME, as in

pkill -INT process-name

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Process – How to Kill Both Process and Subprocess

There is a standard method, if the programs cooperate. Run kill -- -42 where 42 is the pid of the parent process. This sends a signal to all the processes in the process group lead by process 42 (the minus sign before the pid means process group).

Normally, if you run your python script from a shell prompt and it simply forks gnuchess, the two processes should remain in the same process group. But this doesn't seem to be the case, since Ctrl+C sends SIGINT to the whole foreground process group.

Gnuchess might be in its own process group because it made itself a session leader (but I don't know why it would do this), or because you've double-forked it (python forks a shell which forks gnuchess). A double fork is probably avoidable, but I can't tell you how without seeing your code.

A reasonably reliable and POSIX-compliant way of finding the pid of the gnuchess process is

gnuchess_pids=$(ps -A -o pid= -o cmd= | awk '$2 ~ /(^|\/)gnuchess$/ {print $1}')

Specific unix variants may have better ways of achieving this, such as pgrep.

Shell – How to kill two or more processes with one kill command

First of all, check out pkill. You can kill off any number of process given their name:

pkill java

You can even use the full command with arguments as part of the search

pkill -f some_string_in_arguemnts

Secondly, your construct with xargs will work just fine for multiple PID's as long as they are piped in as either space or newline separated numbers.

Best Answer

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Process – How to Kill Both Process and Subprocess

Shell – How to kill two or more processes with one kill command

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