带有 netcat 的 linux 脚本在 x 小时后停止工作 [英] linux script with netcat stops working after x hours

问题描述

我必须编写脚本:

#!/bin/bash

netcat -lk -p 12345 | while read line
do
    match=$(echo $line | grep -c 'Keep-Alive')
    if [ $match -eq 1 ]; then
        [start a command]
    fi
done

和

#!/bin/bash

netcat -lk -p 12346 | while read line
do
    match=$(echo $line | grep -c 'Keep-Alive')
    if [ $match -eq 1 ]; then
        [start a command]
    fi
done

我已经把这两个脚本放在了'/etc/init.d/'

I've put the two scripts in the '/etc/init.d/'

当我重新启动 Linux 机器 (RasbPi) 时，两个脚本都可以正常工作.

When I restart my Linux machine (RasbPi), both the scripts work fine.

我已经尝试了 20 次，它们一直工作正常.

I've tried them like 20 times, and they keep working fine.

但大约 12 小时后，整个系统停止工作.我已经输入了一些登录信息，但脚本似乎不再有反应了.但是当我;

But after around 12 hours, the whole system stops working. I've put in some loggin, but it seems that the scripts are not reacting anymore. But when I;

ps aux

我可以看到脚本仍在运行:

I can see that the scripts are still running:

root      1686  0.0  0.2   2740  1184 ?        S    Aug12   0:00 /bin/bash /etc/init.d/script1.sh start
root      1689  0.0  0.1   2268   512 ?        S    Aug12   0:00 netcat -lk 12345
root      1690  0.0  0.1   2744   784 ?        S    Aug12   0:00 /bin/bash /etc/init.d/script1.sh start
root      1691  0.0  0.2   2740  1184 ?        S    Aug12   0:00 /bin/bash /etc/init.d/script2.sh start
root      1694  0.0  0.1   2268   512 ?        S    Aug12   0:00 netcat -lk 12346
root      1695  0.0  0.1   2744   784 ?        S    Aug12   0:00 /bin/bash /etc/init.d/script2.sh start

重新启动后，他们又开始工作了……但那是一种罪过，定期重新启动 Linux 机器……

After a reboot they start working again... But thats a sin, rebooting a Linux machine periodically...

我已经插入了一些登录信息，这是结果；

I've inserted some loggin, here's the outcome;

Listening on [0.0.0.0] (family 0, port 12345)
[2013-08-14 11:55:00] Starting loop.
[2013-08-14 11:55:00] Starting netcat.
netcat: Address already in use
[2013-08-14 11:55:00] Netcat has stopped or crashed.
[2013-08-14 11:49:52] Starting loop.
[2013-08-14 11:49:52] Starting netcat.
Listening on [0.0.0.0] (family 0, port 12345)
Connection from [16.8.94.19] port 12345 [tcp/*] accepted (family 2, sport 6333)
Connection closed, listening again.
Connection from [16.8.94.19] port 12345 [tcp/*] accepted (family 2, sport 6334)
[2013-08-14 12:40:02] Starting loop.
[2013-08-14 12:40:02] Starting netcat.
netcat: Address already in use
[2013-08-14 12:40:02] Netcat has stopped or crashed.
[2013-08-14 12:17:16] Starting loop.
[2013-08-14 12:17:16] Starting netcat.
Listening on [0.0.0.0] (family 0, port 12345)
Connection from [16.8.94.19] port 12345 [tcp/*] accepted (family 2, sport 6387)
Connection closed, listening again.
Connection from [16.8.94.19] port 12345 [tcp/*] accepted (family 2, sport 6388)
[2013-08-14 13:10:08] Starting loop.
[2013-08-14 13:10:08] Starting netcat.
netcat: Address already in use
[2013-08-14 13:10:08] Netcat has stopped or crashed.
[2013-08-14 12:17:16] Starting loop.
[2013-08-14 12:17:16] Starting netcat.
Listening on [0.0.0.0] (family 0, port 12345)
Connection from [16.8.94.19] port 12345 [tcp/*] accepted (family 2, sport 6167)
Connection closed, listening again.
Connection from [16.8.94.19] port 12345 [tcp/*] accepted (family 2, sport 6168)

谢谢

推荐答案

如果包括 netcat 在内的任何命令都没有从 stdin 读取输入，则可以完全使其独立于终端运行.有时，仍然依赖于终端的后台进程在尝试从后台读取输入时会暂停 (S).实际上，由于您正在运行守护程序，因此您应该确保没有任何命令从它(终端)读取输入.

If none of your commands including netcat reads input from stdin you can completely make it run independent of the terminal. Sometimes background process that are still dependent on the terminal pauses (S) when they try to read input from it on a background. Actually since you're running a daemon, you should make sure that none of your commands reads input from it (terminal).

#!/bin/bash

set +o monitor # Make sure job control is disabled.

(
    : # Make sure the shell runs a subshell.
    exec netcat -lk -p 12345 | while read line  ## Use exec to overwrite the subshell.
    do
        match=$(echo $line | grep -c 'Keep-Alive')
        if [ $match -eq 1 ]; then
            [start a command]
        fi
    done
) <&- >&- 2>&- </dev/null &>/dev/null &

TASKPID=$!
sleep 1s ## Let the task initialize a bit before we disown it.
disown "$TASKPID"

而且我认为我们可以再次尝试记录日志:

And I think we could try the logging thing again:

set +o monitor

(
    echo "[$(date "+%F %T")] Starting loop with PID $BASHPID."

    for (( ;; ))
    do
        echo "[$(date "+%F %T")] Starting netcat."

        netcat -vv -lk -p 12345 | while read line
        do
            match=$(echo "$line" | grep -c 'Keep-Alive')
            if [ "$match" -eq 1 ]; then
                [start a command]
            fi
        done

        echo "[$(date "+%F %T")] Netcat has stopped or crashed."

        sleep 4s
    done
) <&- >&- 2>&- </dev/null >> "/var/log/something.log" 2>&1 &

TASKPID=$!
sleep 1s
disown "$TASKPID"

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