请问$ PWD总是等于$（真实路径。） [英] Does $PWD always equal $(realpath .)

问题描述

由于

• 现代的Linux / UNIX / OSX（W / 的真实路径）


• 庆典（甚至在OSX）4+

• A modern Linux/UNIX/OSX (w/ realpath)
• bash 4+ (even on OSX)

时

"$PWD" == "$(realpath .)"

始终是真的吗？

推荐答案

它是pretty容易测试，这并非总是如此。

It's pretty easy to test that this is not always the case.

$ mkdir /tmp/realdir
$ cd /tmp/realdir
$ echo $PWD
/tmp/realdir
$ ln -s realdir /tmp/fakedir
$ cd /tmp/fakedir
$ echo $PWD
/tmp/fakedir
$ realpath .
/tmp/realdir

所以没有， $ PWD 并不总是相同的 $（真实路径。）。

借助 bash的手动表明 PWD 变量是由内置的 CD 命令设置。默认的href=\"http://www.gnu.org/software/bash/manual/bashref.html#Bourne-Shell-Builtins\" rel=\"nofollow\">行为是：

The bash manual indicates that the PWD variable is set by the built-in cd command. the default behaviour of cd is:

符号链接后违约或带有-l选项

symbolic links are followed by default or with the -L option

这意味着，如果CD插入符号链接的变量被相对于符号链接，而不是相对于物理路径解决。您可以通过使用 -P 选项更改此行为为 CD 命令。这将导致其报告中的 PWD 变量的物理目录：

This means that if you cd into a symlink the variable gets resolved relative to the symlink, not relative to the physical path. You can change this behavior for a cd command by using the -P option. This will cause it to report the physical directory in the PWD variable:

$ cd -P /tmp/fakedir
$ echo $PWD
/tmp/realdir

您可以使用 -P 选项来改变bash中的默认行为：

You can change the default behavior of bash using the -P option:

$ set -P
$ cd /tmp/fakedir
$ echo $PWD
/tmp/realdir
$ set +P
$ cd /tmp/fakedir
$ echo $PWD
/tmp/fakedir

这是当然的，尽管事实上，你可以执行后CD PWD 变量什么>它需要的值：

This is of course notwithstanding the fact that you can assign anything you want to the PWD variable after performing a cd and it takes that value:

$ cd /tmp/fakedir
$ PWD=/i/love/cake
$ echo $PWD
/i/love/cake

但是这不是真的你是问。

but that's not really what you were asking.

这篇关于请问$ PWD总是等于$（真实路径。）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！