Re: [Emacs-diffs] master cfc34c1: Update the way directories are compressed

Re: [Emacs-diffs] master cfc34c1: Update the way directories are compressed

[Stefan Monnier]

>     * lisp/dired-aux.el (dired-compress-file-suffixes): Update the recipe
>       for *.tar.gz decompression to use a pipe.

They look equivalent to me.  Why is the new form better?


        Stefan

Re: [Emacs-diffs] master cfc34c1: Update the way directories are compressed

[Oleh Krehel]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>>     * lisp/dired-aux.el (dired-compress-file-suffixes): Update the recipe
>>       for *.tar.gz decompression to use a pipe.
>
> They look equivalent to me.  Why is the new form better?

The new form doesn't assume that tar supports "-z", as is apparently the
case for non-GNU tar.

    Oleh

Re: [Emacs-diffs] master cfc34c1: Update the way directories are compressed

[Stefan Monnier]

> The new form doesn't assume that tar supports "-z", as is apparently the
> case for non-GNU tar.

Then please add a comment explaining it.  Otherwise someone like me
might be tempted to replace the gzip|tar with "tar -z" on the premise
that it might be more efficient or doesn't require gzip to be in $PATH
or something.


        Stefan "who wonders where we can find a tar that doesn't
                support -z nowadays (ancient Unix? home router?), so
                maybe the comment should include some info about the
                particular circumstance where "tar -z" doesn't exist"

Re: [Emacs-diffs] master cfc34c1: Update the way directories are compressed

[Paul Eggert]

Stefan Monnier wrote:

>          Stefan "who wonders where we can find a tar that doesn't
>                  support -z nowadays (ancient Unix? home router?), so
>                  maybe the comment should include some info about the
>                  particular circumstance where "tar -z" doesn't exist"

How about the central server in my department?

$ tar -czf - /etc/passwd
tar: z: unknown function modifier
Usage: tar {c|r|t|u|x}[BDeEFhilmnopPqTvw@[0-7]][bfk][X...] [blocksize] [tarfile] 
[size] [exclude-file...] {file | -I include-file | -C directory file}...
$ ls -l /usr/sbin/tar
-r-xr-xr-x 1 root bin 77920 Apr 20 2011 /usr/sbin/tar

This is Solaris 10, which is still shipping and which Oracle says it will 
support until at least the year 2021. Solaris 11 added -z, but there are still 
quite a few Solaris 10 hosts out there.

Also, AIX 7.1, the current release, has a tar that lacks -z. I can't easily 
check HP-UX, but wouldn't be surprised if it's like AIX.

Feel free to add this to the comments.