Question

我需要通过netcat或类似的东西发送很多消息。问题是，当我运行echo "something" | netcat ip port时，在收到响应后，连接将继续打开。实际上，连接继续打开，等待新输入。但是，我需要的是在收到响应后关闭连接。看，我的脚本基本上是这样的：

#!/bin/bash
i=1
while [ $i -ne 10000 ];do
    sed -n $[i]p wordlist | netcat localhost 30002 >> result
    i=$[$i+1]
done

如果在打印出结果后可以关闭连接，则一切正常。我知道有一个选项-w“ x”在“ x”秒后关闭连接，但是“ x”的最小值是1且1大于我可以等待的值，我需要尽快关闭连接

Answer 1

很不幸，-q标志对我不起作用。我使用的是“ OpenBSD netcat（Debian补丁程序级别1.187-1ubuntu0.1）”，即使手册中出现了-q标志，也未能如cnicutar的回答中所述起作用。

因此，我的解决方法是：

#!/bin/sh

# POSIX COMPLIANT

HOST="localhost"
PORT=30002

scan () {
    # Ensuring there is no file named msg
    rm msg

    # While msg file doesn't exist or is empty, do
    while [ ! -s msg ]; do
        # Remove instruction from within the loop
        rm msg

        # Append the received messages to msg file, and put the process in the background
        echo "$HOST $PORT" | xargs nc >> msg &

        # If the file exists and is not empty, return, we received the message
        [ -s msg ] && return;

        # A small timeout.. doing some tests I noticed that a timeout of zero sometimes didn't work to catch the message
        # Maybe nc needs a small time to receive everything. You might want to test and increase or decrease this timeout if needed.
        sleep 0.1

        # This script will be spawning a lot of nc process, to kill it before the loop runs again
        pkill -x nc
    done
} 2> /dev/null 

scan

# The function returned, so cat the file
cat msg

# make sure nc is killed
pkill -x nc > /dev/null 2>&1
rm msg

Answer 2

您要寻找的是-q开关。如果您指定：

netcat -q 0 localhost 30002

netcat将立即退出。

收到服务器响应后如何关闭netcat连接？

2 个答案: