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Date: Tue, 21 Apr 2015 02:33:55 +0300
From: Andrey Repin <anrdaemon AT yandex DOT ru>
Reply-To: cygwin AT cygwin DOT com
Message-ID: <1033870684.20150421023355@yandex.ru>
To: Murthy Gandikota <murthy64 AT hotmail DOT com>, cygwin AT cygwin DOT com
Subject: Re: tar zxvf won't  work with Redhat generated compressed tar file
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References: <COL130-W80F61D41DBC766A5C40206C2E00 AT phx DOT gbl>,<969800560 DOT 20150420222609 AT yandex DOT ru>      <COL130-W78804B6BA04135A92CC2FAC2E00 AT phx DOT gbl>,<509379965 DOT 20150420235036 AT yandex DOT ru>  <COL130-W65B445CB84F1010DEEDA6EC2E00 AT phx DOT gbl>,<55356CBB DOT 9030601 AT redhat DOT com>,<COL130-W530B6F57CC449D3CD22F44C2E00 AT phx DOT gbl>  <COL130-W103DBAFD945896AC6F7E51C2E00 AT phx DOT gbl>
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Greetings, Murthy Gandikota!

>>> anything except make a LARGER file - because the first round of
>>> compression removed any redundancy). Tar cannot read a
>>> double-compressed stream, but breaking things into two steps lets you
>>> get back to a single compressed stream, where the tar call then
>>> auto-decompresses because you weren't supplying an explicit 'z' the
>>> second time around. To prove it, try:
>>>
>>> gunzip <mytar.gz>mytar
>>> tar zxvf mytar
>>>
>>> and if it still untars with an explicit decompression, then you have
>>> proven that your original file was double-compressed. Also, if I'm
>>> right about double compression, then mytar.gz would likely be slightly
>>> larger than mytar (rather than the usual case of the .gz being
>>> noticeably smaller).
>>
>> Yes, Sir. It did untar properly. So the problem is with the server compressing during the download (I get the file from a http server)?
>> Thanks a lot for your help

> It would be doubly nice if cygwin handled it ;-) It seems gunzip had no
> problem recognizing the file as double compressed.
> Thanks all for the help.

This is not expected, nor supported. And is unlikely to ever be supported.
Adding "support" for such cases would easily create a shell bomb, if you nest
packers enough times.


-- 
With best regards,
Andrey Repin
Tuesday, April 21, 2015 02:31:44

Sorry for my terrible english...


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