如何在Linux Shell脚本中显示nc返回值?

问题描述

我在如下所示的Linux框中使用 nc 命令来检查端口是否在监听；

I am using nc command in my Linux box like below to check if a port is listening;

这将显示成功消息:

nc -z 192.168.0.2 9000

这将显示0:

echo $?

我已将其组合到如下的shell脚本.sh文件中；

I have combined it in a shell script .sh file like below;

#!/bin/sh
nc -z 192.168.0.2 9000
echo $?

这将显示 1 ，而不是预期的 0 .再说一次，如果我像下面那样修改脚本，它就会起作用；

This displays 1 instead of expected 0. Again, if I modify my script like below, it works;

#!/bin/sh
echo nc -z 192.168.0.2 9000
echo $?

但是这里的问题是，它在类似的位置显示成功消息，然后在下一行显示0.我不想要成功消息，我期望为0.这是什么问题，我该如何解决?

But here the problem is, it displays success message on one like, then displays 0 in next line. I don't want success message, and I am expecting 0. What is wrong here and how can I fix this?

推荐答案

这个小脚本应该可以解决问题:

This small script should do the trick:

#!/bin/bash
SERVER=$1
PORT=$2
nc -z -v -G5 $SERVER $PORT &> /dev/null
result1=$?

#Do whatever you want

if [  "$result1" != 0 ]; then
  echo  port $PORT is closed on $SERVER
else
  echo port $PORT is open on $SERVER
fi

用法:

./myscript.sh servername portnumber

例如:

./myscript www.google.com 80
www.google.com 80
port 80 is open on www.google.com

根据您使用的nc版本，您可能需要将-G调整为-w，因此请进行实验并找出最适合您的

Depending on the version of nc you're using, you may need to adjust the -G to -w, so experiment and find which works best for you.

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