Subject: Bug#4481: Kernel-related dd bug

From: Nikhil Nair <[email-masked]>
Date: Thu, 12 Sep 1996 18:07:58 +0100 (BST)

Package: fileutils
Version: 3.12-4

Under a recent kernel, dd seems to produce spurious extra output *only* if
stdout isn't redirected ...

$ echo 'This is a test.' | dd of=/tmp/testing bs=10k conv=sync
0+1 records in
1+0 records out
$ wc /tmp/testing
      1       5   10240 /tmp/testing
$ dd if=/tmp/testing bs=10k count=1
This is a test.
This is a test.
1+0 records in
1+0 records out
$ dd if=/tmp/testing bs=10k count=1 | cat
This is a test.
1+0 records in
1+0 records out
$ uname -a
Linux amasis 2.0.17 #2 Thu Sep 5 00:58:46 BST 1996 i586
$

On an older kernel (everything else the same):

$ echo 'This is a test.' | dd of=/tmp/testing bs=10k conv=sync
0+1 records in
1+0 records out
$ wc /tmp/testing
      1       5   10240 /tmp/testing
$ dd if=/tmp/testing bs=10k count=1
This is a test.
1+0 records in
1+0 records out
$ dd if=/tmp/testing bs=10k count=1 | cat
This is a test.
1+0 records in
1+0 records out
$ uname -a
Linux amasis 1.3.21 #4 Thu Jan 4 21:02:19 GMT 1996 i586
$

Very odd ...

Nikhil.

--
Nikhil Nair
Trinity College, Cambridge, England
Tel.: +44 1223 368353
Email: [email-masked]
       [email-masked]