I have never seen anybody even come close to isolating what causes some installs to exhibit this problem while other installs do not.

Now you have! :)

But only as a result of your prompting my memory with your post:

C:\test>set PATHEXT=.COM;.EXE;.BAT;.CMD;

C:\test>junk.pl junk.pl
'print "'$_'" while <>;
'
C:\test>junk junk.pl

C:\test>set PATHEXT=.pl;.COM;.EXE;.BAT;.CMD;

C:\test>junk junk.pl
'print "'$_'" while <>;
'
[download]

Personally, I dislike pl2bat with a vengeance. I've tried it several time over the years and always abandoned it almost immediately for one reason or another. I haven't tried to use it now for several years and can't remember all of the reasons.

But the Terminate batch job (Y/N)? prompting is only one.

Another is it screws up syntax highlighting. I could associate .bat with the .pl profile, but then that screws up highlighting in .bats. Another is forgetting that I pl2bat'd some script and the spending a few minutes--or on one particularly memorable occasion a few days--tearing my hair out before working out why none of the changes I was making to the .pl file were affecting the output from the script :)

Dumb! But I've done it several times. There are others. Perl::Tidy etc. Yes. It is just a matter of discipline. And only pl2batting once you've finished developing which is reasonably easy to do. But it's when you come back to something a few months or years later that it goes tits up.

Once you have PATHEXT/ASSOC/FTYPE set up correctly, everything "Just works". And setting it up is a one-time deal. I also like the multiple side-by-side perl installs that it affords through the simple mechanism of using different extensions .pl for 5.latest, .pl8 for 5.8 etc.

One thing you might slightly prefer over using pl2bat might be the following cmd file:

@echo off
setlocal
set cmd=%~f0
set cmd=%cmd:~0,-4%.pl
perl -w %CMD% %*
[download]

This will (try to) invoke a Perl script (ending in .pl) in the same directory and with the same name as the .cmd file this code lives in. You could copy this file besides each Perl script you want to run from the command prompt.

But as you have set up the file associations appropriately already, likely this won't be an issue for you.

C:\test>junk junk.pl

C:\test>
[download]

That's not the behaviour the OP sees. You should be getting an error for that.

>junk junk.pl
'junk' is not recognized as an internal or external command,
operable program or batch file.

>junk < junk.pl
'junk' is not recognized as an internal or external command,
operable program or batch file.

>set PATHEXT=.pl

>junk junk.pl
'print "'$_'" while <>;
'
[download]

I suspect you messed up your test.

I suspect you messed up your test.

Sorry, the absence of error message was simply because I also had a 'junk.bat' in the same directory that did nothing silently. But it doesn't invalidate the premise.

Having deleted that, here is a full re-test in a completely virgin session, that I believe confirms the source of this old 'mystery bug':

Microsoft Windows [Version 6.0.6001]
Copyright (c) 2006 Microsoft Corporation.  All rights reserved.

c:\>cd test

c:\test>set pathext
PATHEXT=.pl;.COM;.EXE;.BAT;.CMD;

c:\test>junk junk.pl
'print "'$_'" while <>;
'
c:\test>junk < junk.pl
'print "'$_'" while <>;
'
c:\test>type junk.pl | junk
'print "'$_'" while <>;
'
c:\test>set pathext=.com;.exe;.bat;.cmd;

c:\test>set pathext
PATHEXT=.com;.exe;.bat;.cmd;

c:\test>junk junk.pl
'junk' is not recognized as an internal or external command,
operable program or batch file.

c:\test>junk < junk.pl
'junk' is not recognized as an internal or external command,
operable program or batch file.

c:\test>type junk.pl | junk
'junk' is not recognized as an internal or external command,
operable program or batch file.

c:\test>set pathexe=%pathext%.pl;

c:\test>set pathext
PATHEXT=.com;.exe;.bat;.cmd;

c:\test>set pathext=%pathext%.pl;

c:\test>set pathext
PATHEXT=.com;.exe;.bat;.cmd;.pl;

c:\test>junk junk.pl
'print "'$_'" while <>;
'
c:\test>junk < junk.pl
'print "'$_'" while <>;
'
c:\test>type junk.pl | junk
'print "'$_'" while <>;
'
c:\test>
[download]

Another is it screws up syntax highlighting.

Ah, yes, the piles of useful tools that I've seen discarded because they get in the way of the syntax coloring crutch continues to grow. I strongly prefer code that is easy to read without the need for colors, especially because I read code in lots of ways (in diff output, in patches, on printed pages, several different ways via revision control systems, etc.) that just don't support syntax coloring. I much prefer to be able to select my tools rather than have one fragile tool eliminating lots of other tools for me. But I realize that this places me in a small minority.

I also don't use Perl::Tidy (for similar reasons: it is rather fragile and I've seen people discard tools because they confuse the poor thing, just as you have, but also because I just don't find much benefit to it). And so using pl2bat doesn't actually require much of any "discipline" for me.

Once you have PATHEXT/ASSOC/FTYPE set up correctly, everything "Just works".

Not for everybody, at least not if you want to use piping or redirection. Or did you already forget the reason for this very thread?

And setting it up is a one-time deal.

Ah, the luxury of only ever running your code on a single computer. I'm now at a job where I have the luxury of not having to deal with a large and ever-growing list of Windows-based computers (the list of Windows-based computers I must deal with is quite small and grows only very slowly).

I also like the multiple side-by-side perl installs that it affords through the simple mechanism of using different extensions .pl for 5.latest, .pl8 for 5.8 etc.

s/simple mechanism/awkward hack/, IMHO. It must take some discipline to come up with a new extension for each new install of Perl and then to remember to update your syntax coloring configuration so that it knows about this growing list of custom extensions. ;) Using something like pl2bat means you pick which Perl to use by actually specifying the perl to use in the script, much like a #! line under Unix. pl2bat doesn't prevent using side-by-side Perl installs. It just affords them in a more straight-forward way.

I also like being able to use bl2bat-wrapped Perl scripts to change the environment or working directory of the calling command prompt (I've posted quite a few of those here). It is also useful for making scripts that can be used by my co-workers even if they don't have Perl installed on their Windows box (because my install of Perl is available via a network share).

By no means am I trying to convince you (or anyone, really) to use pl2bat. I'm just noting why, for me, the down side is so small (just the "Terminate batch job" prompting) and the up side well worth it. :)

- tye