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Path: utzoo!watmath!clyde!burl!ulysses!allegra!mit-eddie!think!harvard!seismo!rochester!cmu-cs-pt!cadre!pitt!darth!investor!rbp
From: rbp@investor.UUCP (Bob Peirce)
Newsgroups: net.unix-wizards
Subject: Re: tar fs copy
Message-ID: <249@investor.UUCP>
Date: Thu, 19-Sep-85 08:18:58 EDT
Article-I.D.: investor.249
Posted: Thu Sep 19 08:18:58 1985
Date-Received: Sat, 21-Sep-85 05:52:43 EDT
References: <832@burl.UUCP> <221@drivax.UUCP> <842@burl.UUCP> <240@investor.UUCP> <233@drivax.UUCP>
Organization: Cookson, Peirce & Co., Pittsburgh, PA
Lines: 31

>> following runs fine.
>> 
>> if [ $# -ne 2 ]
>> then
>> 	echo usage: cphier frompath topath
>> fi
>> exec tar cf - $1 | (cd $2; tar xf - )
> 
> directory it does a fork/exec of mkdir, then waits for all of its
> children to die, including the first tar. Now if the first tar is
> nearly finished then it will write its output to the pipe and exit,
> which allows the second tar to continue. However, if the first tar
> has to write more than what will fit in the pipe then the whole mess
> hangs up, because the first tar is waiting for the second tar to
> read from the pipe, and the second tar is waiting for the first tar
> to exit.

How big is the pipe?  I read somewhere pipes use the root file system,
which on our computer has about 1100 free blocks.  Yet, I have used
cphier to transfer, for example, the entire netnews source, including
rn, from one drive to another.  All I created was the highest level
directory.  Cphier made all the rest.  Will it sometimes work and sometimes
fail on a transfer of this size?
-- 

	 	    Bob Peirce, Pittsburgh, PA
	    uucp: ...!{allegra, bellcore, cadre, idis}
	  	     !pitt!darth!investor!rbp
			    412-471-5320

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