tar fs copy

[Bob Peirce]

>> 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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