batch file - Why does the error message appear when `IF` comparison is in the piped block command?

Question

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

But the next one didn't work,

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

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

more simplified,

This works, (if 3 == 3 echo yes)|sort

This doesn't work, (if 3 NEQ 2 echo yes)|sort

Part of my code.

@echo off
setlocal enabledelayedexpansion
set Unx_path=.....inUnxUtils
(
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/ |/
/g";"s/ //g";"s/~//g"
  ) else (
    echo none
  )
)
)|"%Unx_path%gclip.exe"
exit /b

Answer 1

try this:

set "myline=if 3 NEQ 2 echo yes"

( %myLin^e%)|sort

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

set "myline=if 3 NEQ 2 echo yes"

( %%myLine%%)|sort

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.

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