rem ...
rem (assuming this script is named setup.bat)
if exists setup.bat goto havesetup
echo Can't find myself. Can't install.
goto fail
:havesetup
rem (assuming our perl.exe is in a bin subdirectory)
if not exists perl.exe goto dirsok
echo ZIP file was unpacked without directories. Can't install.
goto fail
:dirsok
if exists bin\perl.exe goto haveperl
echo Missing my perl.exe. Archive damaged? Can't install.
goto fail
:haveperl
rem ...
rem ... use perl to bootstrap itself
rem ...
:fail
pause
:end