bash脚本来启动进程，等待随机，杀进程，重启 [英] Bash script to start process, wait random, kill process, restart

问题描述

我是一个绝对的初学者，想创建一个bash脚本，以随机的命令行程序的启动和退出。我打算在autostart.sh（这里发现了以下有轻微的延迟后自动启动开机（Crunchbang）的脚本：<一href=\"http://interwebworld.co.uk/2011/10/23/how-to-launch-programs-automatically-at-startup-in-crunchbang-linux/\" rel=\"nofollow\">http://interwebworld.co.uk/2011/10/23/how-to-launch-programs-automatically-at-startup-in-crunchbang-linux/ ）

I'm an absolute beginner and am trying to create a bash script to randomize the start and exit of a command line app. I plan to autostart the script on boot (Crunchbang) after a slight delay with the following in autostart.sh (found here: http://interwebworld.co.uk/2011/10/23/how-to-launch-programs-automatically-at-startup-in-crunchbang-linux/ )

(sleep 300s && /home/myuser/Scripts/randomizer.sh) &

这基本上是什么，我需要在randomizer.sh脚本来完成，在一个位伪code的：

This is essentially what I need to accomplish in the randomizer.sh script, in a bit of pseudocode:

start applicationfile
wait a random period of time
if applicationfile is still running
    kill its process
    wait a random period of time
    exit this script and restart this script
else exit this script and restart this script

该randomizer.sh因为我有这到目前为止，哪些我要欢迎一些帮助，如下（含伪code的残余），发现睡眠延迟此处的 http://blog.buberel.org/2010/07/howto-随机睡眠时间，在bash.html

/path/to/applicationfile -s 111.222.333.444 -u username -p password
sleep $[ ( $RANDOM % 150 ) + 60 ]m
if applicationfile is still running
    kill $(ps aux | grep '[u]sername' | awk '{print $2}')
    sleep $[ ( $RANDOM % 150 ) + 60 ]m
    exec $randomizer.sh
else exec $randomizer.sh

我觉得非伪部分应该工作pretty多，因为他们有，但是请大家指正或调整，如果我错了。最初applicationfile命令行的工作，因为它是的，我已经测试过程中杀线，它按预期工作。 Applicationfile没有一个内置的方式，从命令行结束本身，而是在远程机器上的死连接会在5分钟被杀死局部后杀死，所以它杀死在本地满足我的需求是可以接受的。

I "think" the non-pseudo parts should work pretty much as they are, but please correct me or adjust if I'm wrong. The initial applicationfile command line works as it is, and I already tested the process kill line and it works as expected. Applicationfile doesn't have a built-in way to end itself from commandline, but the dead connection on the remote machine will be killed after 5 minutes of being killed locally, so killing it locally is acceptable for my needs.

我没有什么任何想法如何处理是杀，检查如果的过程是在第一个位置运行上面的行。对不起，文字的墙上，但我想证明我所做的，就像我已经能够。

What I don't have any idea how to handle is the line above the kill, which checks "if" the process is running in the first place. Sorry for the wall of text but I wanted to show I've done as much as I could already.

推荐答案

在bash中， $！是最后一个推出进程的PID，这样的东西沿着线图案这应该工作：

In bash, $! is the PID of the last launched process, so something patterned along the lines of this should work:

mycommand &
last_pid=$!
sleep( $RANDOM )
kill -KILL $last_pid

您当然可以，反复折腾来改变你发送的信号，$ RANDOM和你想睡觉的时间之间的关系，等等。

You can, of course, fiddle around to change the signal you send, the relationship between $RANDOM and the time you want to sleep, etc.

这有点不太可能，一个新的进程将得到同样的PID，除非或者a）睡眠时间很长或b）你的机器推出了很多短期的过程。在Linux上，PID被用32765一个最大循环分配的，因此，粗略地讲，你将不得不纷纷推出关于睡眠时间冒险击中属于不同的工艺相同的PID，许多进程。如果这是一个风险，你可以添加一个测试（从技术上讲，有一个在这里的比赛，但它不太可能是一个问题）。下面好像它会做你想做的。

It's somewhat unlikely that a new process will get the same PID unless either a) the sleep time is very long or b) your machine launches a lot of short-lived processes. On Linux, PIDs are allocated cyclically with a max of 32,765, so, roughly speaking, you would have to have launched about that many processes in the sleep time to risk hitting the same PID belonging to a different process. If that's a risk, you could add a test (technically, there's a race here, but it's very unlikely to be a problem). The following seems like it would do what you want.

signal=KILL

sleep_a_while () {
    sleep $[ ( $RANDOM % 150 ) + 60 ]m
}

while true; do
    # Note: command launched in background:
    /path/to/applicationfile -s 111.222.333.444 -u username -p password &

    # Save PID of command just launched:
    last_pid=$!

    # Sleep for a while:
    sleep_a_while

    # See if the command is still running, and kill it and sleep more if it is:
    if ps -p $last_pid -o comm= | grep -qs '^applicationfile$'; then
        kill -$signal $last_pid 2> /dev/null
        sleep_a_while
    fi

    # Go back to the beginning and launch the command again
done

我已经取代了自我 - EXEC 用等效循环

在杀行标准错误的重定向到的/ dev / null的是因为一场比赛的期望。该进程可能的时间之间自然退出 PS 完成，时间的杀被执行，导致无害错误信息。这场比赛是不可避免的（无害），除非该PID的存在和信号的发送测试是一致的。

On the kill line, the redirect of stderr to /dev/null is desirable because of a race. The process might exit naturally between the time the ps completes and the time that the kill is executed, resulting in a harmless error message. This race is unavoidable (and harmless) unless the test that the PID exists and the sending of the signal are coincident.

如果有拟以最多的有一个的 applicationfile 在同一时间运行，则可以完全通过更换回避本场比赛的一个实例：

If there is intended to be at most one instance of applicationfile running at a time, then this race can be avoided entirely by replacing:

# See if the command is still running, and kill it and sleep more if it is:
if ps -p $last_pid -o comm= | grep -qs '^applicationfile$'; then
    kill -$signal $last_pid 2> /dev/null
    sleep_a_while
fi

使用：

killall -q applicationfile && sleep_a_while

如果这个不能用，测试的基思·雷诺兹的变种比较好，因为它避免了不必要的的grep ，即使用：

If this cannot be used, Keith Reynolds's variant of the test is better, since it avoids an unnecessary grep, i.e. using:

# See if the command is still running, and kill it and sleep more if it is:
if [ "$(ps -p $last_pid -o comm=)" = "applicationfile" ]; then
    kill -$signal $last_pid 2> /dev/null
    sleep_a_while
fi

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