zenity --auto-kill:杀死subshel​​l不会杀死其子进程吗? [英] zenity --auto-kill: Killing a subshell does not kill its child processes?

问题描述

我很难理解zenity --progress --auto-kill的行为.它似乎不是杀死其父进程的子进程，而是以某种方式分离它们.

I am having a really hard time understanding the behaviour of zenity --progress --auto-kill. It appears to not kill its parent process' subprocesses but to detach them somehow.

考虑以下shell脚本long-live-the-subshell.sh:

Consider the following shell script long-live-the-subshell.sh:

#!/bin/sh
(
    echo sleeping...>&2;
    sleep 5;
    echo woke up >&2 
)  | zenity --progress --auto-close --auto-kill

要重现上述行为:

• 执行脚本sh long-live-the-subshell.sh
• 点击进度栏上的取消
• 再等5秒钟
• 看到woke up输出到终端

• execute the script sh long-live-the-subshell.sh
• click Cancel on the progress bar
• wait another 5 seconds
• see that woke up is output to the terminal

示例输出:

> sh long-live-the-subshell.sh 
sleeping...
Hangup
> woke up

Hangup会在您单击取消时发生.然后，您会得到提示.但是，sleep 5完成后，woke up将输出到终端.

The Hangup happens when you click Cancel. You then get your prompt back. However, after the sleep 5 finishes, woke up is output to the terminal.

ps jf:

 PPID   PID  PGID   SID TTY      TPGID STAT   UID   TIME COMMAND
20806 20825 20825 20825 pts/7     2391 Ss    1000   0:01 -zsh
20825  2391  2391 20825 pts/7     2391 S+    1000   0:00  \_ sh test.sh
 2391  2392  2391 20825 pts/7     2391 S+    1000   0:00      \_ sh test.sh
 2392  2394  2391 20825 pts/7     2391 S+    1000   0:00      |   \_ sleep 5
 2391  2393  2391 20825 pts/7     2391 Sl+   1000   0:00      \_ zenity --progress --auto-close --auto-kill

点击取消后立即

ps jf:

 PPID   PID  PGID   SID TTY      TPGID STAT   UID   TIME COMMAND
 1179  2392  2391 20825 pts/7    20825 S     1000   0:00 sh test.sh
 2392  2394  2391 20825 pts/7    20825 S     1000   0:00  \_ sleep 5

很明显，zenity杀死了它的PPID(在这种情况下为2391)，但是以某种方式2391的其他两个子项(2392和其唯一的子sleep命令2394)仍然有效.为什么? kill -1 2391不应该(显然是 zenity会做什么) )还会杀死2391的孩子吗?

Apparently, zenity kills its PPID (2391 in this case) but somehow both of the other children of 2391 (2392 and its only child sleep command 2394) stay alive. Why? Shouldn't a kill -1 2391 (which is obviously what zenity does) kill also the children of 2391?

推荐答案

我刚刚找到了一种对我有用的好方法，并且我认为使用bash在大多数情况下应该适用.

I have just found a nice way that works for me, and I think should work for most cases, using bash.

这个想法是您在带有陷阱的容器中运行Zenity:zenity --auto-kill将SIGHUP发送到父进程时，父进程在死前将SIGHUP发送到同一进程组中的所有进程.所以关键是这样称呼Zenity:

The idea is that you run Zenity in a container with a trap: when zenity --auto-kill sends a SIGHUP to the parent process, the parent process sends a SIGHUP to all processes in the same process group before dying. So the key is calling Zenity like this:

{
    trap 'pkill -g 0' HUP
    zenity --progress --auto-kill
}

在下面的代码中，我展示了如何将它与命名管道Feed Zenity一起使用，如果希望运行的过程在标准输出上生成数据，这将使事情变得更容易.

In the code below I show how I used this with a named pipe feeding Zenity, which makes things easier if you want the running process to produce data on standard output.

#! /bin/bash

...

zenityfifo=/tmp/zenityfifo$$
trap "rm --force $zenityfifo" EXIT

if [ -x /usr/bin/zenity -a "$DISPLAY" ]; then
    rm --force $zenityfifo
    mkfifo $zenityfifo
    ## The while loop is needed to keep the pipe blocking on read
    while read p < $zenityfifo; do echo $p; done | {
    trap 'pkill -g 0' HUP
    zenity --progress --title="resync" --auto-close --auto-kill
    } &
fi

while ...; do
    ...
    echo ... > $zenityfifo
done

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