[Python-Dev] Re: FWD: Re: Problem w/ IDLE on Win2000

[Guido van Rossum]

> [Kurt B. Kaiser, struggles to get an embedded-space spawn to work]

[Tim, can't belp helping]
> I think the trick is that you shouldn't quote the executable path at all.
> Under the covers, MS takes the executable name as-is, passing it as the
> lpApplicationName argument to the Win32 CreateProcess(), but squashes all
> your *arguments* into a single string, which gets passed on as the
> lpCommandLine argument to CreateProcess().
> 
> In the arguments, you should avoid the cleverness of trying to quote only
> the part(s) with a space(s).  Stick a double quote on each end of each
> argument, and that's it(*).
> 
> So, for example, I made a copy of a wc.exe into
> 
>     c:\Program Files\tmp\w c.exe
> 
> and then this Python works (on Win98SE(*)) to run that program on itself:
> 
> """
> raw = r'C:\Program Files\tmp\w c.exe'
> 
> import os
> print os.path.exists(raw)
> 
> decorated = '"%s"' % raw
> os.spawnv(os.P_NOWAIT, raw, (decorated, decorated))
> """
> 
> Here's the output:
> 
> C:\Code\python\PCbuild>python temp2.py
> True
>      26     203   13824 C:\Program Files\tmp\w c.exe
> 
> C:\Code\python\PCbuild>
> 
> So I expect that IDLE is getting in trouble because it's not stuffing quotes
> around an *argument* to a program it's spawning.
> 
> 
> (*) There the fun begins.  While os.system() spawns a command shell,
>     I don't think spawnv() does.  Which would be a real help here.
>     Win9x use command.com by default, and Windows after that use
>     cmd.exe.  They have have different quoting rules, and cmd.exe
>     actually has two different sets of quoting rules (triggered by
>     an option to cmd.exe, and/or by a registry setting).
> 
>     Still, I haven't tried the program above on a Win2K (etc)
>     system, and somebody should before you get optimistic.  In one
>     of cmd.exe's quoting nightmare modes, whether double quotes
>     get stripped actually depends on the content of the quoted
>     string <arghghghgh>!

Right.  I'm pretty sure that the quoting rules are different on 9x/Me
on the one hand and on NT/2K/XP OTOH (though the real reason may be
the different default shell).  For example, on my 98se laptop, in a
DOS shell,

  cd \Program Files

says

  Too any parameters - files

while this works on the XP (still -- Red Hat Linux 9.0 coming soon :-)
box at work.

--Guido van Rossum (home page: http://www.python.org/~guido/)