bash与函数调用中的命令替换 [英] Command substitution in bash vs function calling

问题描述

我正在从一本书中编写一个shell脚本，并且有一个示例，其中我创建一个函数并稍后使用 $(function_name)调用该函数.

I am writing a shell script from a book, and there is an example where I am creating a function and invoking that function later with $(function_name).

但是据我所知，我可以通过写一个函数名称来调用它.那么，使用名称和 $(function_name)调用函数之间有什么区别?

But as far as I know, I can invoke a function by just writing its name. So, what is the difference between calling a function with its name and with $(function_name)?

推荐答案

$(...)被称为命令替换.

简单地说， function_name 将完​​成输出.

Simply put, function_name will print the output, done.

$(function_name)函数的输出将成为要执行的新命令的一部分(通常作为参数).

$(function_name) the output from the function will become a part (usually as an argument) as a new command to be executed.

echo "ls"  #<--- assume this is the function

打开一个终端，然后尝试一下，您会更好地理解它:

Open a terminal, and give this a try, you will understand it better:

echo "ls"

和

$(echo "ls")

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