> To make this even more idiot proof .. I'd like to purge all older entries from PATH

I dont see the point: if you prepend your desired perl to PATH (as portableshell.bat does) there is almost no risk of collision: only a call to a make flavour not present in the first distribution can lead to problems. I mean: if you cast perl5.34 and this does not contains nmake (just as example) but this executable is present in perl5.10 just few entry onward in PATH ..so this can be a problem. It seems to me a very advanced usage so probably not your (collegues) case.

If you are already using portableshell.bat you can simply hardcode your desired PATH modifying the line..

    set PATH=%~dp0perl\site\bin;%~dp0perl\bin;%~dp0c\bin;%PATH%

    # ...to something like

    set PATH=%~dp0perl\site\bin;%~dp0perl\bin;%~dp0c\bin;c:\Windows;C:
+\Windows\System32;
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The above is generally enough.

In more customized scenarios you can reuse other ENV entries to build up your final PATH for example:

HOMEDRIVE=C:

ProgramFiles=C:\Program Files
ProgramFiles(x86)=C:\Program Files (x86)
ProgramW6432=C:\Program Files

windir=C:\WINDOWS
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PS more on this:

> off course I could spawn a perl one-liner, but the basic idea of BAT is to keep the delay minimal

Perl is already here and used, so if you prefere perl over batch (;) you can use it to change $ENV{PATH} you only need to modify the perl oneliner aimed to print nice stuff on screen:

# line 24 of portableshell.bat

perl -MConfig -e "printf("""Perl executable: %%s\nPerl version   : %%v
+d / $Config{archname}\n\n""", $^X, $^V)" 2>nul
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I hope File::Spec can handle weird windows names correctly using path separtor and the idiom @PATH = File::Spec->path();

L*