On 05/29/2017 08:36 AM, David Wright wrote:
On Mon 29 May 2017 at 06:59:23 (-0500), Richard Owlett wrote:
I think the is a subtle bug in the man page.
I introduces the two lines of code saying:
> Sending a USR1 signal to a running 'dd' process makes it print
> I/O statistics to standard error and then resume copying.
I believe that to accurately describe the code at
https://www.gnu.org/software/coreutils/manual/html_node/dd-invocation.html#dd-invocation
*NOT* the code on the man page.
The two lines you quote don't "introduce" anything. They describe
the action of dd when you send a USR1 signal to it, a primary
purpose of the man page.
I realize now that was the discrepancy that prompted my question.
I had gone to the man page to double check syntax. Spotted the code
a thought "a way to display progress information when copying".
I can "sort of" understand syntactically correct code. The less said
of my programming skills the better ;/ How I "read" the code just
didn't jibe with the description.
Am I correct that there is a problem with the man page?
Not that I can see. A terse illustration of program output might
be seen as an infrequent but welcome addition to a man page.
However, others might prefer not to lengthen the man page (which
is a one chunk affair) with tutorials, or even examples,
preferring to leave that for info nodes or other more extensive
documentation.
Cheers,
David.
Not quite. It says "...and then resume copying."
The script copies bytes until the second line is encountered.
It outputs data and *STOPS DEAD*
richard@stretch-2nd:~$ dd if=/dev/zero of=/dev/null& pid=$!
[1] 3600
richard@stretch-2nd:~$ kill -USR1 $pid; sleep 1; kill $pid
53590611+0 records in
53590610+0 records out
27438392320 bytes (27 GB, 26 GiB) copied, 21.6988 s, 1.3 GB/s
richard@stretch-2nd:~$
