如何等待使用netcat的开放端口? [英] How to wait for an open port with netcat?

问题描述

我正在尝试用jenkins创建一个自定义dockerfile.我会等到8080端口打开，而不是用netcat做一个丑陋的"sleep 60"，但是对bash脚本和netcat不太有信心.

I'm trying to do a custom dockerfile with jenkins on it. I would to wait until port 8080 is open instead of doing an ugly 'sleep 60' with netcat but in not very confident with bash scripts and netcat.

以下是我要执行的操作的示例:

Here is an example of what i'm trying to do:

#!/bin/bash

opened=0

while [ "$opened"  == "0" ]; do
  echo "Waiting jenkins to launch on 8080..."
  nc -vz localhost 8080
done

echo "Jenkins launched"

推荐答案

您不能将netcat设置为等到某个端口打开后再等待，因此您必须添加部分内容以等待下一次检查.试试这个:

You can't set netcat to wait until some port is open, so you have to add part for waiting before next check is made. Try this:

#!/bin/bash

echo "Waiting jenkins to launch on 8080..."

while ! nc -z localhost 8080; do   
  sleep 0.1 # wait for 1/10 of the second before check again
done

echo "Jenkins launched"

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