linux – 检查从同一bash脚本启动的后台进程的运行状态

发布时间：2020-12-14 00:35:26 所属栏目：Linux 来源：网络整理

导读：我必须编写一个bash脚本,根据传递的命令行参数在后台启动进程,如果成功运行启动程序则返回. 这是我想要实现的伪代码 if [ "$1" = "PROG_1" ] ; then ./launchProg1 if [ isLaunchSuccess ] ; then echo "Success" else echo "failed" exit 1 fielif [ "$1" =

我必须编写一个bash脚本,根据传递的命令行参数在后台启动进程,如果成功运行启动程序则返回.

这是我想要实现的伪代码

if [ "$1" = "PROG_1" ] ; then
    ./launchProg1 &
    if [ isLaunchSuccess ] ; then
        echo "Success"
    else
        echo "failed"
        exit 1
    fi
elif [ "$1" = "PROG_2" ] ; then
    ./launchProg2 &
    if [ isLaunchSuccess ] ; then
        echo "Success"
    else
        echo "failed"
        exit 1
    fi
fi

脚本不能等待或睡眠,因为它将由另一个关键任务c程序调用,并且需要高吞吐量(每秒没有启动进程),而且进程的运行时间未知.脚本既不需要捕获任何输入/输出,也不需要等待已启动的进程完成.

我没有成功尝试以下方法：

#Method 1
if [ "$1" = "KP1" ] ; then
    echo "The Arguement is KP1"
    ./kp 'this is text' &
    if [ $? = "0" ] ; then
        echo "Success"
    else
        echo "failed"
        exit 1
    fi
elif [ "$1" = "KP2" ] ; then
    echo "The Arguement is KP2"
    ./NoSuchCommand 'this is text' &
    if [ $? = "0" ] ; then
        echo "Success"
    else
        echo "failed"
        exit 1
    fi
#Method 2
elif [ "$1" = "CD5" ] ; then
    echo "The Arguement is CD5"
    cd "doesNotExist" &
    PROC_ID=$!
    echo "PID is $PROC_ID"
    if kill -0 "$PROC_ID" ; then
        echo "Success"
    else
        echo "failed"
        exit 1
    fi
#Method 3
elif [ "$1" = "CD6" ] ; then
    echo "The Arguement is CD6"
    cd .. &
    PROC_ID=$!
    echo "PID is $PROC_ID"
    ps -eo pid | grep "$PROC_ID" && { echo "Success"; exit 0; }
    ps -eo pid | grep  "$PROC_ID" || { echo "failed" ; exit 1; }
else
    echo "Unknown Argument"
    exit 1
fi

运行脚本会产生不可靠的输出.方法1,2总是返回成功,而方法3在检查之前完成流程执行时返回失败.

这是在GNU bash上测试的示例,版本4.1.2(1)-release(x86_64-redhat-linux-gnu)和GNU bash,版本4.3.11(1)-release(x86_64-pc-linux-gnu)

[scripts]$./processStarted3.sh KP1
The Arguement is KP1
Success
[scripts]$./processStarted3.sh KP2
The Arguement is KP2
Success
./processStarted3.sh: line 13: ./NoSuchCommand: No such file or directory
[scripts]$./processStarted3.sh CD6
The Arguement is CD6
PID is 25050
failed

正如类似问题所示,我不能使用进程名称,因为one process may be executed several times和others无法应用.

我没有尝试过screen和tmux,因为获得在生产服务器上安装它们的权限并不容易(但如果这是剩下的唯一选择,那么会这样做)

UPDATE
@ghoti
./kp是存在的程序,启动程序返回Success. ./NoSuchCommand不存在.从(编辑过的)输出中可以看出,脚本错误地返回Success.

进程完成执行或程序异常终止时无关紧要.通过脚本启动的程序不会以任何方式进行跟踪(因此我们不会将pid存储在任何表中,也不会出现使用deamontools的必要性).

@Etan Reisner
无法启动的程序示例是./NoSuchCommand,它不存在.或者可能是一个无法启动的损坏的程序.

@Vorsprung
调用在后台启动程序的脚本不需要很多时间(并且可以按照我们的期望进行管理).但是睡眠1会随着时间的推移累积而引起问题.

前面提到的#Method3可以很好地限制在ps -eo pid |之前终止的限制进程grep“$PROC_ID”&& {echo“成功”;退出0;可以执行检查.

解决方法

这是一个示例,它将显示一个过程的结果,无论它是否成功启动.

#!/bin/bash
$1 & #executes a program in background which is provided as an argument
pid=$! #stores executed process id in pid
count=$(ps -A| grep $pid |wc -l) #check whether process is still running
if [[ $count -eq 0 ]] #if process is already terminated,then there can be two cases,the process executed and stop successfully or it is terminated abnormally
then
        if wait $pid; then #checks if process executed successfully or not
                echo "success"
        else                    #process terminated abnormally
                echo "failed (returned $?)"
        fi
else
        echo "success"  #process is still running
fi

#Note: The above script will only provide a result whether process started successfully or not. If porcess starts successfully and later it terminates abnormally then this sciptwill not provide a correct result

（编辑：李大同）

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