Re: untar.m on Solaris with non-GNU tar

[Bill Denney]

On Fri, 20 Oct 2006, John W. Eaton wrote:

> On 20-Oct-2006, Bill Denney wrote:
>
> | I'm working on something that will fix this.  It will use the command:
> |
> | sprintf("(cd \"%s\"; gzip -d -c \"%s\" | tar -x -v)", directory, filename);
>
> Is this to fix the untar command, or for the unpack command?

I was making unpack into a central driver where untar, unzip, gunzip, and 
bunzip2 could all just pass their input into unpack since the operations 
are all the same:

validate the input
get the url if needed
execute a command
parse the output to get a file list

> Is directory "." unless the optional outputdir argument is given?

Yes.

> This will all break unless we have a POSIX shell, since I don't think
> the Windows command shell does subshells the same way as a POSIX
> shell.
>
> If we care about Windows (and apparently some people do) then we need
> to write these kinds of things in portable ways.  Does that mean we
> need to do ugly things like
>
>  if (isunix ())
>    unix ("...");
>  elseif (ispc ())
>    dos ("...");
>  else
>    error ("I have no clue how to execute an external command");
>  endif

We can do something like is currently done in untar:

orig_dir = pwd ();

unwind_protect
  chdir (directory);
  [status, output] = system (sprintf ("tar -x -v -f %s", tarfile));
unwind_protect_cleanup
  chdir (orig_dir);
end_unwind_protect

> Or we have to decide that the way to achieve portability is to ensure
> that Octave has a POSIX shell available to run external commands.  But
> even that might not be enough, as filesystem differences may cause
> trouble unless we are careful.

I don't think we have to worry about a POSIX shell all the time.  I can do 
the above and it should work.  Piping output works in windows, and that's 
all that's required.

Bill

--
"I could never sleep my way to the top
because my alarm clock always wakes me right up."
  -- "Hey, Mr. DJ...", They Might Be Giants