如何从另一个 Windows 批处理脚本调用一个 Windows 批处理脚本并在两者中延迟扩展

Question

我有两个.bat 文件，都使用延迟扩展，所以我可以在for循环中设置变量。

下面的例子被大大简化了，只是为了说明问题

脚本one.bat

@echo off

setlocal enableextensions
setlocal enabledelayedexpansion

set j=0
for /L %%i in (1,1,2) do (
  set j=%%i
  set /A j=!j! + 1
  echo %%i !j!
  two.bat
  echo %%i !j!
)

脚本two.bat

@echo off

setlocal enableextensions
setlocal enabledelayedexpansion

echo Hello World

exit /B 0

从two.bat 返回时，变量!j! 丢失，echo 重新打开。

J:\>one
1 2
Hello World
1 !j!

J:\>(
set j=2
 set /A j=!j! + 1
 echo 2 !j!
 two.bat
 echo 2 !j!
)
Missing operator.
2 !j!
Hello World
2 !j!

是的，我可以将 two.bat 设为 one.bat 中的子例程，但它有数百行，我不想维护相同逻辑的两个副本

我在这里错过了什么？

Answer 1

您的假设是错误的，即执行从文件 two.bat 返回，因为只有当您使用 call command¹ 时才会出现这种情况。

批处理文件 one.bat 在括号中的代码块中运行 two.bat，该代码块已经在命令堆栈² 中，因此该块在终止执行之前（有点）完成。

---

你的输出完美地说明了发生了什么（因此我在这里评论它）：

J:\>one              
1 2                  /* first loop iteration, the first `echo %%i !j!` in the block is
                        executed as expected; */
Hello World          /* `two.bat` is run; execution does NOT return to `one.bat`,
                        because there is NO `call`, which would put a return point onto
                        the stack! the only thing remembered and thus accomplished is
                        the current command line or parenthesised block; */
1 !j!                /* the second `echo %%i !j!` in the block is executed as it is
                        still buffered, but `two.bat` is already quit, hence implicit
                        `endlocal` commands have been executed, so all the nested
                        `setlocal` commands in your scripts are cancelled and delayed
                        expansion is disabled (default state); moreover, variable `j` is
                        no longer defined here; */
                     /* at this point, the parenthesised block, which is the loop body,
                        has been executed, hence batch file context is left and Command
                        Prompt context applies, so `@echo off` from `one.bat` does no
                        longer apply here; */
J:\>(                // this block is nothing but the echo of the second loop iteration,
set j=2              // which is still buffered;
 set /A j=!j! + 1    
 echo 2 !j!          
 two.bat             
 echo 2 !j!          
)                    
Missing operator.    /* this error message is caused by the attempt to execute
                        `set /A j=!j! + 1` (remember that delayed expansion is no longer
                        enabled and `j` is undefined); */
2 !j!                // first `echo %%i !j!` in the buffered second loop iteration;
Hello World          /* `two.bat` is run again; afterwards, batch file context is left
                        again and Command Prompt context applies; */
2 !j!                // second `echo %%i !j!` in the buffered second loop iteration;

要证明执行是在批处理文件还是命令提示符上下文下，只需将set /A j作为最后一个命令放在one.bat的循环体中，这样您将在输出1 !j!之后得到额外的输出0第二个2 !j!，因为set /A 在批处理文件上下文中不返回任何内容，但它在命令提示符上下文中输出（最后一个）结果（没有尾随换行符）； 0 的值表明 j 不再设置。

---

_{1) 有几个例外：被调用的批处理文件涉及到管道，或者被for /F loop 运行和解析，因为批处理文件在这样的新cmd.exe 实例中运行
2) 如果调用的批处理文件包含在具有串联命令的行中，情况也是如此，因此在执行two.bat 时，two.bat & echo Fine 之类的内容会回显Fine .}