@echo off
for /f "delims=U" %%i in ('cmd /u /c echo 唉') do set "tab=%%i"
setlocal enabledelayedexpansion
(for /f "delims=" %%i in (a.txt) do (
if defined str (
echo,!str!%tab%%%i&set "str="
) else set "str=%%i"
)
if defined str echo !str!
)>处理后.txt
pause