Create unique file name Windows batch

Question

I have seen many posts about creating a unique filename from the naive %TIME% to the plausible (but insufficient) %RANDOM%. Using wmic os get localdatetime is m

Answer 1

@echo off
:: generate a tempfilename in %1 (default TEMPFILE)
:loop
set /a y$$=%random%+100000
set y$$=temp%y$$:~1,2%.%y$$:~-3%
if exist "%temp%\%y$$%" goto loop
SET "y$$=%temp%\%y$$%"© nul "%temp%\%y$$%" >nul 2>NUL
:: y$$ now has full tempfile name
if "%1"=="" (set "tempfile=%y$$%") else (set "%1=%y$$%")

Here's a cut-down version of my tempfile generator to create a file named tempnn.nnn in the %temp% directory.

Once tempnn.nnn has been created, then it's simple to create as many further tempfiles as you like for the process by appending a suffix to %y$$%, eg %y$$%.a etc. Of course, that presumes that some other process doesn't randomly create filenames without using this procedure.