按预期别名“CD”与子shell不工作命令 [英] Alias to 'cd' Command with Subshell Not Working as Expected

问题描述

我刚刚得知在bash别名。我创建了一个像这样：

I just learned about aliases in bash. I created one like so:

别名为CD $目录

其中， $目录是使用的输入。在另一个shell脚本，我可以启动一个子shell像这样：

where $directory is from use input. In another shell script, I can launch a subshell like so:

（庆典）

这使我到子shell，在那里，如果我跑 CD ，我去了别名， CD $目录。这是伟大的，它似乎是按预期工作。

which brings me to the subshell, where, if I run cd, I go to the alias, cd $directory. This is great and it seems to be working as expected.

我要找的是当子shell启动时，CD自动发生，所以我尝试：

What I'm looking for is for when the subshell is launched, the cd happens automatically, so I tried:

（庆典| CD）

以为这将启动子shell和CD的用户输入 $目录，但它不工作。我该如何去获得这个工作？我也试过（bash的-c CD）无济于事。

thinking it would launch the subshell and cd to the user-entered $directorybut it's not working. How can I go about getting this to work? I also tried ( bash -c cd) to no avail.

感谢。

推荐答案

之所以（庆典| CD）不工作是管道中的每个命令在一个单独的子shell中运行，因此（庆典| CD）基本上等同于（（庆典）|（CD））（但后者甚至推出的更多的子shell，当然）。相反，你应该能够写：

The reason that ( bash | cd ) doesn't work is that each command in a pipeline is run in a separate subshell, so ( bash | cd ) is essentially equivalent to ( ( bash ) | ( cd ) ) (except that the latter launches even more subshells, of course). Instead, you should be able to write:

( cd ; bash )

（运行 CD 的前的运行庆典），因为庆典将继承它从启动子shell的执行环境的一个副本。

(which runs cd before running bash) since bash will inherit a copy of the execution environment of the subshell it was launched from.

顺便说一句＆MDASH;你确定你想要创建 CD 作为别名这种方式？这似乎容易出错和混乱给我。我认为这将是更好地创建 CD s到用户指定的目录下的shell函数：

By the way — are you sure you want to create cd as an alias this way? That seems error-prone and confusing to me. I think it would be better to create a shell function that cds to the user-specified directory:

function cd_user () { cd "$directory" ; }

( cd_user ; bash )

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