Re: It cannot select the compression tool while reading from stdin

[Sergey Poznyakoff]

Hi Vincenzo,

That's a normal and documented behavior.  Quoting GNU Tar Manual,
subsection 8.1.1 "Creating and Reading Compressed Archives":

   The only case when you have to specify a decompression option while
   reading the archive is when reading from a pipe or from a tape drive
   that does not support random access.  However, in this case GNU 'tar'
   will indicate which option you should use.  For example:

     $ cat archive.tar.gz | tar tf -
     tar: Archive is compressed.  Use -z option
     tar: Error is not recoverable: exiting now

Regards,
Sergey