如何检查进程 ID (PID) 是否存在 [英] How to check if a process id (PID) exists

问题描述

在 bash 脚本中，我想执行以下操作(在伪代码中):

In a bash script, I want to do the following (in pseudo-code):

if [ a process exists with $PID ]; then

    kill $PID 

fi

条件语句的适当表达式是什么?

What's the appropriate expression for the conditional statement?

推荐答案

要检查进程是否存在，请使用

To check for the existence of a process, use

kill -0 $pid

但正如@unwind 所说，如果您希望它在任何情况下都终止，那么就

But just as @unwind said, if you want it to terminate in any case, then just

kill $pid

否则你会遇到竞争条件，在第一个 kill -0 之后进程可能会消失.

Otherwise you will have a race condition, where the process might have disappeared after the first kill -0.

如果你想忽略kill的文本输出并根据退出代码做一些事情，你可以

If you want to ignore the text output of kill and do something based on the exit code, you can

if ! kill $pid > /dev/null 2>&1; then
    echo "Could not send SIGTERM to process $pid" >&2
fi

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