[Darkar25]

Проблема решена!Финальный код:

Код:

@echo off
setlocal enableextensions enabledelayedexpansion

set /a "NUM=0"
set /a "STR=0"
set /p "Question="

:Repeat
set /a NUM+=1
set /a c=0
for /f "UseBackQ Delims=" %%A IN ("123.txt") do (
  set /a c+=1
  if !c!==%NUM% set "STR=%%A"
)
echo.!STR!
echo.!STR! | >nul findstr.exe /C:%Question% && echo Yes || goto :Repeat

endlocal
pause
exit /b 0