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Path: utzoo!mnetor!lsuc!ncrcan!brian
From: brian@ncrcan.UUCP (Brian Onn)
Newsgroups: comp.unix.xenix
Subject: Re: extracting tar.Z BBS files
Message-ID: <297@ncrcan.UUCP>
Date: Tue, 11-Aug-87 11:02:26 EDT
Article-I.D.: ncrcan.297
Posted: Tue Aug 11 11:02:26 1987
Date-Received: Wed, 12-Aug-87 05:48:22 EDT
References: <249@bvax.UUCP>
Reply-To: brian@ncrcan.UUCP ()
Organization: NCR Canada Ltd., Mississauga, Ontario
Lines: 27

In article <249@bvax.UUCP> rich@bvax.UUCP (Rich Chahley) writes:
>
>I'm having trouble extracting ...tar.Z files off of The CONSULTANTS' EXCHANGE
>(uucp: conexch 714-842-5851 login: nuucp).  I can successfully download files
>such as "emacs38.tar.Z" but cannot extract the files from the "tar" format.
...
>  resulting messages are.... tar: blocksize=20        (normal message)
>                        .... tar: directory checksum error
>
>Richard Chahley
>{allegra, ihnp4, decvax, pyramid, watmath} !utzoo!bnr-vpa!bnrnuns!ngpt!rich

I came across this same problem, when I realized what was causing it.  I (and
I suspect you are) was using a xmodem protocol to download the file.
Unfortunately, xmodem does not create files that are the *exact* length of
the file downloaded, but are actually multiples of 128 bytes (the xmodem
blocksize).  Compress will uncompress the file without complaining, but
the resulting tar file is longer than it should be. Thus tar will try to read
some data at the end of the tar file, but it doesn't make sense...hence
'directory checksum error'.   The trick is to download a compressed tar file
with a protocol that properly retains file sizes after the download.   I
use YMODEM, with 1k block sizes, and have downloaded,uncompressed, and
'untarred' with no problems ever since.   I don't know whether or not
kermit maintains file sizes, but I didn't have much luck with kermit
and compressed tar files.

Hope this helps,