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提取函数内部的 nc_pid 变量的值

tag-icon • tag-icon bash process variable
提取函数内部的 nc_pid 变量的值

我想更新，nc_pid这样我就可以用它来检查带有 pid 的进程是否nc_pid正在运行。

#!/usr/bin/bash

function start () {
    trap 'echo "Clean up and exit"; kill $nc_pid; exit' TERM
    exec > outfile
    exec 2> errfile
    exec 0< /dev/null

    while true; do
        (nc -lkp 1234 -e /usr/bin/bash &>/dev/null) &
        nc_pid=$!                 # global variable nc_pid is not updated
        wait $nc_pid
        kill $nc_pid &>/dev/null
    done
}

if [ "$1" != "__forked__" ]; then
        setsid "$0" __forked__ "$@" &
        exit
else
        shift
fi

# stop or start daemon
nc_pid=999999

case "$1" in
    stop)
    killall simpled.sh
    ;;
    start)  
    if ! kill -0 $nc_pid &>/dev/null            # always false
    then
        start
    fi
    ;;
    status)
    if kill -0 $nc_pid &>/dev/null              # always false
    then
        echo "nc running"
    else
        echo "nc not running"
    fi
    ;;
    *)
    echo -e "\nsimpled.sh [start|stop|status]"
    ;;
esac

最初nc_pid设置为通常不存在的值 (999999)。然后我想在运行时nc_pid更新分叉nc进程的 pid。start()但似乎nc_pid根本没有更新（值保持为 999999）。

因此$0 start总是启动分叉进程的新实例nc并$0 status始终输出“nc not running”。

如何修复代码，以便从外部nc_pid获取分叉进程的 pid ？谢谢！ncstart()

答案1

我只是将 nc 的 pid 保存到文件中并以这种方式修复它。

#!/usr/bin/bash

function start () {
    trap 'echo "Clean up and exit"; kill $nc_pid; rm nc_pid; exit' TERM
    exec > outfile
    exec 2> errfile
    exec 0< /dev/null

    while true; do
        (nc -lkp 1234 -e /usr/bin/bash &>/dev/null) &
        nc_pid=$!
    echo $nc_pid > nc_pid
        wait $nc_pid
        kill $nc_pid &>/dev/null
    done
}

if [ "$1" != "__forked__" ]; then
        setsid "$0" __forked__ "$@" &
        exit
else
        shift
fi

# stop or start daemon

([ ! -f "nc_pid" ] && nc_pid=9999) || nc_pid=$(cat nc_pid) 

case "$1" in
    stop)
    killall simpled.sh
    ;;
    start)  
    if ! kill -0 $nc_pid &>/dev/null
    then
        start
    fi
    ;;
    status)
    if kill -0 $nc_pid &>/dev/null
    then
        echo -e "\nnc running: pid $nc_pid"
    else
        echo -e "\nnc not running"
    fi
    ;;
    *)  
        # when $0 is run, the help message displays then won't return to terminal until return key is pressed.
    echo -e "\nsimpled.sh [start|stop|status]" 
    ;;
esac

干杯!

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