Re: master 6d6bf46 2/2: Make dired-do-compress work for *.tar.gz files

[Eli Zaretskii <eliz@gnu.org>]

> From: Oleh Krehel <ohwoeowho@gmail.com>
> Date: Thu, 15 Oct 2015 15:07:08 +0200
> Cc: emacs-devel@gnu.org
> 
> Achim Gratz <Stromeko@nexgo.de> writes:
> 
> > This is what a reasonably recent GNU tar offers:
> >
> >  Compression options:
> >
> >   -a, --auto-compress        use archive suffix to determine the compression
> >                              program
> 
> Thanks, Achim.
> 
> For creating archives I propose that we use:
> 
>     (defcustom dired-compress-command
>       "tar -caf %i.tar.gz %i"
>       "The default command for creating archives from directories.
>     %i denotes the directory name.")
> 
> which would translate to:
> 
>     tar -caf foo.tar.gz foo/
> 
> And leave it up to the user to customize this command.

Isn't the -a option GNU Tar specific?  I don't think we ever
hard-coded GNU/Linux specific options, thus forcing all users of all
the other systems to customize Emacs.  In other cases (like "M-x
grep") we probe the command for support of non-portable options, and
only use them if supported.  Let's not deviate from that practice
here.

Thanks.