字符串拼接的批处理

@echo off
:: 每6行拼接为一行，剩余的不够6行的显示在最后一行
::
::
set num=0
setlocal enabledelayedexpansion
for /f "delims=" %%i in (a.txt) do (
set /a num+=1
set str=!str! %%i
if !num! equ 6 echo !str! set num=0 set str=
)
if not "%str%"=="" echo %str%
pause