如何将变量的值保留在使用“延迟扩展本地”的Windows批处理脚本之外模式？ [英] How to keep the value of a variable outside a Windows batch script which uses "delayed expansion local" mode?

问题描述

上下文：我需要调用Windows批处理脚本，通过添加另一个路径' xxx来更新我的 PATH




没有任何重复

（if我添加' xxx '到PATH，像' aaa; xxx; bbb '，我需要一个更新的 PATH 喜欢' aaa; bbb; xxx '）

没有任何聚合

（我可以重复地调用脚本，而不用' aaa; bbb; xxx; xxx; xxx; ... '）

我尝试过：

以下函数负责重复任务， / p>

 ：cleanAddPath  - 从PATH中删除％〜1，将其添加到PATH结尾
 SETLOCAL ENABLEDELAYEDEXPANSION 
设置PATH =！PATH：％〜2 =！ 
 set PATH =！PATH：;; =;！ 
设置PATH =％PATH％;％〜2 
设置P =！P：;; = 
 echo％PATH％
 echo ------------- 
 ENDLOCAL 
退出/ b 
  / pre> 
 
 
但是，它需要 延迟扩展本地模式，这意味着：在脚本结束（或这里，函数结束时 cleanAddPath ），任何为％PATH％设置的东西被抛弃。
 
 
 
我可以问用户为此，您可以使用 cmd / V：ON 选项启动 cmd （激活延迟扩展，否则关闭默认），但这是不实际的。
 
 
 
如何修改 PATH 变量的方式我在上面描述过，并且在调用脚本后，在我当前的DOS会话中仍然有更新
解决方案
页面 DOS  - 功能集合 提供了一个函数如何在DOS中返回值的很好的例子，即使使用延迟扩展模式：
 
 
 
以下函数将使用添加 PATH 更新所需的任何变量：
 ：cleanAddPath  - 从％〜1中删除％〜2，将其添加到％〜1 
的结尾SETLOCAL ENABLEDELAYEDEXPANSION 
设置P =！％〜1！ 
设置P =！P：％〜2 =！ 
设置P =！P：;; =;！ 
设置P =！P！;％〜2 
设置P =！P：;; = 
（ENDLOCAL& REM .-- RETURN VALUES 
 SET％〜1 =％P％
）
退出/ b 
  
注意使用的路径的并置。作为 jeb   comments ：
 
 
如果您的路径包含&code> C：\中的&符号，那么行设置P =％P％;％〜2 是至关重要的文件&设置。
 
更改更改设置 P =！P！;％〜2 。 > 
 
  SET％〜1 =％P％是允许记住（使用％〜1 表示的变量）您使用延迟扩展功能设置的值。
 
我最初使用 SET％〜1 =％P％！，但 jeb  comments：
 
 
命令 SET％〜1 =％P％！可以简化为 SET％〜1 =％P％，因为尾部感叹号在延迟扩展模式中仅具有（良好）效果，如果您准备％P％ before。
 
 
要更新您的 PATH 变量，您可以调用您的功能与：
 调用：cleanAddPath PATHC：\my\path\to\add
  
在离开该脚本后，将持续存在您当前的DOS会话。
 
 
 
  dbenham 的答案指出一个更强大的答案（upvoted），但在我的情况下，这个脚本就够了。
 
Context: I need to call a Windows batch script which would update my PATH by adding another path 'xxx' at the end of it, but:


without any duplicate

(if I add 'xxx' to a PATH like 'aaa;xxx;bbb', I need an updated PATH like 'aaa;bbb;xxx')
without any aggregation

(I can call the script repeatedly without ending up with 'aaa;bbb;xxx;xxx;xxx;...')


What I have tried:

The following function takes care of any duplicate and does the job
:cleanAddPath -- remove %~1 from PATH, add it at the end of PATH
SETLOCAL ENABLEDELAYEDEXPANSION
set PATH=!PATH:%~2=!
set PATH=!PATH:;;=;!
set PATH=%PATH%;%~2
set P=!P:;;=;!
echo %PATH%
echo -------------
ENDLOCAL  
exit /b
But, it needs delayed expansion local mode, which means: at the end of the script (or here, at the end of the function cleanAddPath), whatever has been set for %PATH% is thrown away.

I could ask the users (for which I write the script) to launch their cmd with a cmd /V:ON option (activating the delayed expansion, otherwise off by default), but that is not practical.

How can I modify the PATH variable the way I described above, and still have it updated in my current DOS session after calling said script?
解决方案
The page "DOS - Function Collection" gives great example on how a function can return a value in DOS, even when using delayed expansion mode:

The following function will update any variable you want with an addition PATH:
:cleanAddPath -- remove %~2 from %~1, add it at the end of %~1
SETLOCAL ENABLEDELAYEDEXPANSION
set P=!%~1!
set P=!P:%~2=!
set P=!P:;;=;!
set P=!P!;%~2
set P=!P:;;=;!
(ENDLOCAL & REM.-- RETURN VALUES
  SET "%~1=%P%"
)
exit /b
Note the concatenation of paths using. As jeb comments:

  
The line set P=%P%;%~2 is critical if your path contains ampersands like in C:\Documents&Settings.

  Better change to set "P=!P!;%~2".
The SET "%~1=%P%" is the part which allows to memorize (in the variable represented by %~1) the value you have set using delayed expansion features.

I initially used  SET "%~1=%P%" !, but jeb comments:

  
The command SET "%~1=%P%" ! could be simplified to SET "%~1=%P%" as the trailing exclamation mark has only a (good) effect in delayed expansion mode and if you prepared %P% before.
To update your PATH variable, you would call your function with:
call :cleanAddPath PATH "C:\my\path\to\add"
And it will persists after leaving that script, for your current DOS session.

dbenham's answer points to a more robust answer (upvoted), but in my case this script is enough.

                        
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