批处理文件的奇怪行为

Question

我有两个cmd文件.child.cmd:

@echo off
exit 1

parent.cmd:

@echo off
cmd /C child.cmd
if %errorlevel% EQU 0 (
   echo OK
) else (
   echo ERROR
)

如果要运行parent.cmd,则将打印ERROR.

但如果稍微更改parent.cmd,那么将打印OK:

@echo off
if "YES" EQU "YES" (
   cmd /C child.cmd
   if %errorlevel% EQU 0 (
      echo OK
   ) else (
      echo ERROR
   )
)

为什么在第二个例子中打印好了？

Answer 1

在您需要delayed expansion访问的代码块内%variables%:

 @echo off &setlocal enabledelayedexpansion
 if !errorlevel! EQU 0 (