shell 编程中的 $(command) 和 `command` 有什么区别? [英] What is the difference between $(command) and `command` in shell programming?

问题描述

要将命令的输出作为变量存储在 sh/ksh/bash 中，您可以执行以下任一操作

To store the output of a command as a variable in sh/ksh/bash, you can do either

var=$(command)

或

var=`command`

这两种方法有什么区别?

What's the difference if any between the two methods?

推荐答案

反引号/墓碑已被弃用，取而代之的是 $() 用于命令替换，因为 $() 可以像 $(echo foo$(echo bar)) 一样轻松地嵌套在自身中.还有其他差异，例如反斜杠在反引号/gravemark 版本中的解析方式等.

The backticks/gravemarks have been deprecated in favor of $() for command substitution because $() can easily nest within itself as in $(echo foo$(echo bar)). There are other differences such as how backslashes are parsed in the backtick/gravemark version, etc.

请参阅 BashFAQ/082 的几个原因总是更喜欢$(...) 语法.

See BashFAQ/082 for several reasons to always prefer the $(...) syntax.

另见POSIX 有关各种差异的详细信息的规范.

Also see the POSIX spec for detailed information on the various differences.

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