为什么在管道块命令中进行“IF”比较时会出现错误消息？ [英] Why does the error message appear when `IF` comparison is in the piped block command?

问题描述

我简化了代码。
以下三个是工作。

I simplified the code. The following three are work.

for /L %a in (1,1,9) do @(if %a NEQ 0 (echo %a))

&

for /L %a in (1,1,9) do @(if not %a == 0 (echo %a))

&

(for /L %a in (1,1,9) do @(if not %a == 0 (echo %a)))|sort /R

但下一个不起作用，

(for /L %a in (1,1,9) do @(if %a NEQ 0 (echo %a)))|sort /R

管道阻止命令中 NEQ 的问题是什么？

What's the problem of NEQ in the piped block command?

更简化，

这有效，（如果3 == 3回显是）| sort

这不起作用，（如果3 NEQ 2 echo yes）| sort

我的部分代码。

@echo off
setlocal enabledelayedexpansion
set Unx_path=.....\bin\UnxUtils\
(
for /F %%a in ('^""%Unx_path%pclip.exe"^|"%Unx_path%sed.exe" -r "s/^^$/none/"^|"%Unx_path%sed.exe" -rf "script_file"^"') do @(
  if not "%%a" == "none" (
    "%Unx_path%grep.exe" -iEe "%%a" "file4search"|"%Unx_path%sed.exe" -r "s/^^[^,]+$/,&/";"s/^^([^.]+)[.][^.]+$/\1/"|"%Unx_path%gawk.exe" "BEGIN{FS=\",\";ORS=\" \"}{print $2}"|"%Unx_path%sed.exe" "s/%%a//I g";"s/.*/%%a &|/";"s/ -/ /g";"s/ |/\n/g";"s/ /\t/g";"s/~/\t/g"
  ) else (
    echo none
  )
)
)|"%Unx_path%gclip.exe"
exit /b

推荐答案

试试这个：

set "myline=if 3 NEQ 2 echo yes"

( %myLin^e%)|sort

或来自批处理文件（双重扩展与批处理文件和控制台的工作方式不同）：

or from batch file (double expansion works differently from batch file and the console):

set "myline=if 3 NEQ 2 echo yes"

( %%myLine%%)|sort

神秘由jeb 这里和此处。虽然你在管道之前遇到了这个问题，但它是同一个bug，因为cmd在管道的每一边创建了两个线程。

The "mystery" was solved by jeb here and here . Though you are facing the issue before the pipe it is the same bug because the cmd creates two threads on each side of the pipe.

以下是for循环的制作方法工作：

Here's how the for loop can be made to work:

set "line=if %a NEQ 0"
(for /L %a in (1,1,9) do @( %lin^e% echo %a))|sort /R

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