batch-file - 使环境变量在 ENDLOCAL 中存活

Question

我有一个批处理文件，它通过一系列中间变量计算变量:

@echo off
setlocal

set base=compute directory
set pkg=compute sub-directory
set scripts=%base%\%pkg%\Scripts

endlocal

%scripts%\activate.bat

最后一行的脚本没有被调用，因为它在 endlocal 之后，它破坏了 scripts环境变量，但它必须在 endlocal 之后，因为它的目的是设置一堆其他环境变量供用户使用。

我如何调用一个脚本，其目的是设置永久环境变量，但谁的位置由临时环境变量确定？

我知道我可以在 endlocal 之前创建一个临时批处理文件并在 endlocal 之后调用它，如果没有其他问题，我会这样做，但我想知道是否有一个不那么令人畏缩的解决方案。

Answer 1

ENDLOCAL & SET VAR=%TEMPVAR%图案很经典。但也有不理想的情况。

如果您不知道 TEMPVAR 的内容，那么如果该值包含特殊字符(如 <)，您可能会遇到问题。 > &或 | .您通常可以通过使用像 SET "VAR=%TEMPVAR%" 这样的引号来防止这种情况发生。 ，但是如果有特殊字符并且值已经被引用，这可能会导致问题。

如果您担心特殊字符，则 FOR 表达式是跨越 ENDLOCAL 屏障传输值的绝佳选择。延迟扩展应在 ENDLOCAL 之前启用，并在 ENDLOCAL 之后禁用。

setlocal enableDelayedExpansion
set "TEMPVAR=This & "that ^& the other thing"
for /f "delims=" %%A in (""!TEMPVAR!"") do endlocal & set "VAR=%%~A"

限制:

如果在 ENDLOCAL 之后启用延迟扩展，那么如果 TEMPVAR 包含 !，最终值将被破坏。 .

无法传输包含换行符的值

如果您必须返回多个值，并且您知道某个字符不能出现在任一值中，那么只需使用适当的 FOR/F 选项。例如，如果我知道这些值不能包含 | :

setlocal enableDelayedExpansion
set "temp1=val1"
set "temp2=val2"
for /f "tokens=1,2 delims=|" %%A in (""!temp1!"|"!temp2!"") do (
   endLocal
   set "var1=%%~A"
   set "var2=%%~B"
)

如果必须返回多个值，并且字符集不受限制，则使用嵌套的 FOR/F 循环:

setlocal enableDelayedExpansion
set "temp1=val1"
set "temp2=val2"
for /f "delims=" %%A in (""!temp1!"") do (
  for /f "delims=" %%B in (""!temp2!"") do (
    endlocal
    set "var1=%%~A"
    set "var2=%%~B"
  )
)

一定要退房 jeb's answer一种安全、防弹的技术，适用于所有情况下的所有可能值。

2017-08-21 - 新功能 RETURN.BAT
我曾与 DosTips 用户 jeb 合作开发 a batch utility called RETURN.BAT可用于退出脚本或被调用的例程并跨越 ENDLOCAL 屏障返回一个或多个变量。很酷 :-)

下面是代码的 3.0 版。我很可能不会更新此代码。最好按照链接确保您获得最新版本，并查看一些示例用法。

RETURN.BAT

::RETURN.BAT Version 3.0
@if "%~2" equ "" (goto :return.special) else goto :return
:::
:::call RETURN  ValueVar  ReturnVar  [ErrorCode]
:::  Used by batch functions to EXIT /B and safely return any value across the
:::  ENDLOCAL barrier.
:::    ValueVar  = The name of the local variable containing the return value.
:::    ReturnVar = The name of the variable to receive the return value.
:::    ErrorCode = The returned ERRORLEVEL, defaults to 0 if not specified.
:::
:::call RETURN "ValueVar1 ValueVar2 ..." "ReturnVar1 ReturnVar2 ..." [ErrorCode]
:::  Same as before, except the first and second arugments are quoted and space
:::  delimited lists of variable names.
:::
:::  Note that the total length of all assignments (variable names and values)
:::  must be less then 3.8k bytes. No checks are performed to verify that all
:::  assignments fit within the limit. Variable names must not contain space,
:::  tab, comma, semicolon, caret, asterisk, question mark, or exclamation point.
:::
:::call RETURN  init
:::  Defines return.LF and return.CR variables. Not required, but should be
:::  called once at the top of your script to improve performance of RETURN.
:::
:::return /?
:::  Displays this help
:::
:::return /V
:::  Displays the version of RETURN.BAT
:::
:::
:::RETURN.BAT was written by Dave Benham and DosTips user jeb, and was originally
:::posted within the folloing DosTips thread:
:::  http://www.dostips.com/forum/viewtopic.php?f=3&t=6496
:::
::==============================================================================
::  If the code below is copied within a script, then the :return.special code
::  can be removed, and your script can use the following calls:
::
::    call :return   ValueVar  ReturnVar  [ErrorCode]
::
::    call :return.init
::

:return  ValueVar  ReturnVar  [ErrorCode]
:: Safely returns any value(s) across the ENDLOCAL barrier. Default ErrorCode is 0
setlocal enableDelayedExpansion
if not defined return.LF call :return.init
if not defined return.CR call :return.init
set "return.normalCmd="
set "return.delayedCmd="
set "return.vars=%~2"
for %%a in (%~1) do for /f "tokens=1*" %%b in ("!return.vars!") do (
  set "return.normal=!%%a!"
  if defined return.normal (
    set "return.normal=!return.normal:%%=%%3!"
    set "return.normal=!return.normal:"=%%4!"
    for %%C in ("!return.LF!") do set "return.normal=!return.normal:%%~C=%%~1!"
    for %%C in ("!return.CR!") do set "return.normal=!return.normal:%%~C=%%2!"
    set "return.delayed=!return.normal:^=^^^^!"
  ) else set "return.delayed="
  if defined return.delayed call :return.setDelayed
  set "return.normalCmd=!return.normalCmd!&set "%%b=!return.normal!"^!"
  set "return.delayedCmd=!return.delayedCmd!&set "%%b=!return.delayed!"^!"
  set "return.vars=%%c"
)
set "err=%~3"
if not defined err set "err=0"
for %%1 in ("!return.LF!") do for /f "tokens=1-3" %%2 in (^"!return.CR! %% "") do (
  (goto) 2>nul
  (goto) 2>nul
  if "^!^" equ "^!" (%return.delayedCmd:~1%) else %return.normalCmd:~1%
  if %err% equ 0 (call ) else if %err% equ 1 (call) else cmd /c exit %err%
)

:return.setDelayed
set "return.delayed=%return.delayed:!=^^^!%" !
exit /b

:return.special
@if /i "%~1" equ "init" goto return.init
@if "%~1" equ "/?" (
  for /f "tokens=* delims=:" %%A in ('findstr "^:::" "%~f0"') do @echo(%%A
  exit /b 0
)
@if /i "%~1" equ "/V" (
  for /f "tokens=* delims=:" %%A in ('findstr /rc:"^::RETURN.BAT Version" "%~f0"') do @echo %%A
  exit /b 0
)
@>&2 echo ERROR: Invalid call to RETURN.BAT
@exit /b 1


:return.init  -  Initializes the return.LF and return.CR variables
set ^"return.LF=^

^" The empty line above is critical - DO NOT REMOVE
for /f %%C in ('copy /z "%~f0" nul') do set "return.CR=%%C"
exit /b 0