[comp.unix.ultrix] dd and tar problem

wyman@athertn.Atherton.COM (Wyman Chong) (09/19/90)

Does anybody know if this is a bug?

I am having problems trying to use dd and tar under either Ultrix 3.1D or 4.0
running on a DECStation 3100.

When writing to the tape drive using tar everything is OK.
However if I try the following:

pluto:wyman{8}:tar cvf /dev/rmt0h good fdact.c

a good 16 blocks 
a fdact.c 55 blocks 

pluto:wyman{12}:dd if=/dev/rmt0h | tar tvf -
4+0 records in
4+0 records out
tar: blocksize = 4
rw-r--r-- 2150/0    8113 Aug 30 15:39 1990 good


tar: Directory checksum error, possible file name:
Atherton Technology.
*------------------------------------------------------------------------


From the looks of it If I create a tape using tar I can extract it with tar
However, if I extract it using dd I have problems. I was able to extract it
using dd if I created it using dd. The reason I need dd is that I want to
be able to do something like....

rsh tapemachine "dd if=/dev/rmt0h" | tar xvf -

This used to work under 3.1 (I think) but does not work under
3.1D or 4.0. This also works under SunOS.

Any ideas?

Wyman Chong
Atherton Technology
wyman@atherton.com
{decwrl,sun}!athertn!wyman

avolio@decuac.DEC.COM (Frederick M. Avolio) (09/20/90)

Try specifying a block size on the dd command.  Works for me...

% dd bs=10240 if=/dev/rmt0h | tar tvf -

Fred