Re: command.com versus cmd.exe

[Zhongtao Zhu <zhongtao@tsinghua.edu.cn>]

Kai.Grossjohann@CS.Uni-Dortmund.DE (Kai Großjohann) writes:

> I don't use Windows myself, but I think that some versions of Windows
> use command.com as interpreter for commands and others use cmd.exe.
> Is this true?
> 
> If it is true, how would a Lisp package know which one to use?
> shell-file-name?  system-type?

In Emacs source tree there is a nt/ directory containing support for
compiling and running GNU Emacs on MS Windows 95/98/nt/xp. I'd like to
cite two paragraphs from cmdproxy.c as follows:

   Accepts subset of Unix sh(1) command-line options, for
   compatability with elisp code written for Unix.  When possible,
   executes external programs directly (a common use of /bin/sh by
   Emacs), otherwise invokes the user-specified command processor to
   handle built-in shell commands, batch files and interactive mode.

   The main function is simply to process the "-c string" option in
   the way /bin/sh does, since the standard Windows command shells use
   the convention that everything after "/c" (the Windows equivalent
   of "-c") is the input string.

I think this would be a hint to Kai's question. 

By building Emacs from the nt/ directory in MS Windows, every thing
works successfully well. I now check the variable `shell-file-name' in
my machine it is set with "D:/emacs/bin/cmdproxy.exe".

In other experiment I've performed by net-install the pre-compiled
binaries without X11 in MS Windows, the installed Emacs when running
in cmd.exe seems insane since it cannot even be terminated by C-x
C-c. I wonder if this is exactly related to Kai's hesitation.
-- 
Zhongtao Zhu                          Tel: +86 10 6278 2266
Department of Computer, Tsinghua University, Beijing, China