<<<是什么?以bash表示的平均值(即，在socat ...<<<""字符串>>输出文件名中) [英] What does <<< mean in bash (ie. in socat ... <<<"string" >output-filename)

问题描述

我试图理解一个代码库，在其中看到如下所示的行: socat /tmp/haproxy - <<< "show servers state" > /var/state/haproxy/global

socat在这里做什么? <<<是什么意思?

解决方案

socat命令在文件/tmp/haproxy和stdin之间创建双向管道，该管道通过将-传递给socat来表示./p>

实际上，它将stdin附加到/tmp/haproxy并将结果输出写入/var/state/haproxy/global

<<<是一项bash功能，即所谓的 此处为字符串 .它将字符串"show server state"作为标准输入传递给socat.

I am trying to understand a codebase where I see a line like below: socat /tmp/haproxy - <<< "show servers state" > /var/state/haproxy/global

What is socat doing here? What does <<< mean?

解决方案

The socat command creates a bidirectional pipe between the file /tmp/haproxy and stdin which is expressed by passing - to socat.

In fact it appends stdin to /tmp/haproxy and writes the resulting output to /var/state/haproxy/global

<<< is a bash feature, a so called here string. It passes the string "show server state" as stdin to socat.

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