bug#10990: 24.0.94; Uncompressing files

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sun, 11 Mar 2012 09:23:11 +0100
> From: Dani Moncayo <dmoncayo@gmail.com>
> 
> I am on a MS Windows 7 OS.  All the GNU/Unix-like tools that I
> currently have/need come from a MinGW/MSYS installation.
> 
> I've tried the "Z" command from a dired buffer (to compress a file).
> The compression goes well, but when I try to uncompress the same file,
> I get the error message: "Searching for program: no such file or
> directory, gunzip".

Evidently, you don't have gunzip, at least not on PATH.  Or maybe it's
MSYS revenge day: perhaps you do have gunzip, but it's a shell script
or some such.  Anyway, copying gzip.exe into gunzip.exe should be all
you need. 

> However:
> * I can visit the compressed file, which implies an implicit
> uncompression.  So if Emacs is able to uncompress the file in this
> case, why does it fail in other cases?

Visiting compressed files uses "gzip -d", so it doesn't need gunzip.
See lisp/jka-cmpr-hook.el.

> * If I open a cmd.exe console and do "gzip -d my_file", the file is
> uncompressed without problems.

Another evidence to the same effect.

> The docstring of the "Z" command says nothing about customizing the
> way of performing the uncompression, and the current way doesn't work
> for me.  So I'd like to ask for (a) a better way of finding the
> uncompression utility and (b) a way of customizing the command to
> perform the uncompression.

I submit that your system is misconfigured, but of course I won't
object if someone makes a defcustom out of
dired-compress-file-suffixes.