@echo off
set ff=a.txt
echo.正在处理,请稍候...
for /f "usebackq delims=" %%a in ("%ff%")do call :y "%%a"
(for /f "tokens=1* delims==" %%b in ('set #')do echo.%%c)>"%ff%"
echo OK 处理完毕
ping -n 2 127.1>nul
exit
:y
set r=%random%
if defined #%r% goto y
set #%r%=%~1