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Re: Trying to understand man page for dd

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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 $pid
53590611+0 records in
53590610+0 records out
27438392320 bytes (27 GB, 26 GiB) copied, 21.6988 s, 1.3 GB/s
richard@stretch-2nd:~$

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Trying to understand man page for dd Richard Owlett <rowlett@cloud85.net> - 2017-05-28 14:00 +0200
  Re: Trying to understand man page for dd JPlews <jw@plews.org.uk> - 2017-05-28 14:10 +0200
    Re: Trying to understand man page for dd Richard Owlett <rowlett@cloud85.net> - 2017-05-28 14:30 +0200
    Re: Trying to understand man page for dd Ulf Volmer <u.volmer@u-v.de> - 2017-06-02 00:00 +0200
      Re: Trying to understand man page for dd Curt <curty@free.fr> - 2017-06-03 14:00 +0200
  Re: Trying to understand man page for dd The Wanderer <wanderer@fastmail.fm> - 2017-05-28 14:10 +0200
    Re: Trying to understand man page for dd Richard Owlett <rowlett@cloud85.net> - 2017-05-28 14:30 +0200
  Re: Trying to understand man page for dd "Thomas Schmitt" <scdbackup@gmx.net> - 2017-05-28 14:50 +0200
    Re: Trying to understand man page for dd Richard Owlett <rowlett@cloud85.net> - 2017-05-28 15:00 +0200
  Re: Trying to understand man page for dd David <bouncingcats@gmail.com> - 2017-05-29 02:50 +0200
    Re: Trying to understand man page for dd "Thomas Schmitt" <scdbackup@gmx.net> - 2017-05-29 08:30 +0200
      Re: Trying to understand man page for dd Richard Owlett <rowlett@cloud85.net> - 2017-05-29 14:10 +0200
        Re: Trying to understand man page for dd David Wright <deblis@lionunicorn.co.uk> - 2017-05-29 15:40 +0200
          Re: Trying to understand man page for dd Richard Owlett <rowlett@cloud85.net> - 2017-05-29 16:20 +0200
            Re: Trying to understand man page for dd "Thomas Schmitt" <scdbackup@gmx.net> - 2017-05-29 17:20 +0200
            Re: Trying to understand man page for dd David Wright <deblis@lionunicorn.co.uk> - 2017-05-29 17:20 +0200
        Re: Trying to understand man page for dd David <bouncingcats@gmail.com> - 2017-05-30 04:30 +0200
    Re: Trying to understand man page for dd mbroe@oakland.edu - 2017-05-31 15:20 +0200

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