linux kill命令-9 vs -15 [英] linux kill command -9 vs -15

问题描述

我有一个要杀死的进程，然后重新启动服务.有人编写了一段代码，通过编写以下脚本来终止该过程

I have a process that i would like to kill and then restart a service. Someone has written a code to kill the process by writing the following set of scripts

ps -ef |grep "process_name" | awk '{print "kill -15 " $2}'> /projects/test/kill.sh
#run the kill script
/projects/test/kill.sh

然后再次

ps -ef |grep "process_name" | awk '{print "kill -9 " $2}'> /projects/test/kill.sh
#run the kill script
/projects/test/kill.sh

#finally
service restart command here     
# the problem here is that service does not restart properly sometimes, 
as it thinks that process is still running.

据我了解，kill -15会优雅地终止进程.但是马上他们也有杀死-9的能力.所以如果一个进程在第一个命令中被杀死，当 kill -9 也在同一个进程上运行时会发生什么?还是ps -ef甚至会列出该进程，因为它已被标记为杀死?

As i understand kill -15 gracefully kills the process. But then right away they have the kill -9 as well. So if a process was getting killed in the first command, what happens when kill -9 is also run on the same process? Or will the ps -ef even list out that process since it has been marked for kill?

谢谢！

推荐答案

您正确地认为 kill -15 是优雅地杀死进程.但是，杀死一个进程是瞬间发生的.因此，上面的程序将检查 pid ，尝试优雅地将其杀死..如果 kill -15 失败-The > kill -9 被执行.知道 kill -15 失败的方法是 grep 命令.如果 kill -15 成功，则该 pid 应该不再存在，从而使以下 grep 返回空.

You are correct that kill -15 is to gracefully kill a process. But, killing a process is something that happens instantaneously. So the program above is going to check for pid, attempting to kill it gracefully .. If the kill -15 fails -- The kill -9 is performed. The way it knows that kill -15 failed, is the grep command. If kill -15 was successful, that pid should not exist any longer, making the following grep return empty.

实际上，仅当 kill -15 无法正常停止程序时， kill -9 才运行.这种方法的问题在于，有时根据程序的不同，正常停止进程可能需要一些时间.所以恕我直言，需要等待一段时间或 sleep 几秒钟，以允许 kill -15 尝试优雅地停止进程.. 最有把握使用上述方法，几乎总是调用 kill -9 ，因为该脚本没有太多时间可以正常关闭该进程.如果 kill -15 仍在处理，kill -9 将覆盖并立即停止进程.

So really, kill -9 only runs if kill -15 failed to gracefully stop the program. The problem with this approach, is that sometimes gracefully stopping a process can take some time depending on the program. So IMHO there needs to be a wait period or a sleep for a few seconds to allow kill -15 to attempt to gracefully stop the process .. Most assuredly with the approach above, kill -9 is almost always invoked since the script doesn't allow much time for the process to be shut down properly. In the event that kill -15 is still processing, kill -9 will just override and instantly stop the process.

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