[COFF] Re: Shell script advice: using 'dd' to write multiple media

[steve jenkin <sjenkin@canb.auug.org.au>]

Ralph,

Nice solution:
	examine dd’s STDERR then ‘break’.

Thanks for the test script - I like your generation of characters using ‘dc’.

cheers!
steve

> On 27 Jun 2023, at 16:23, Ralph Corderoy <ralph@inputplus.co.uk> wrote:
> 
> Hi Steve,
> 
>> I’ve never figured out how to use ‘dd’ so it returns after a single
>> block is written doesn’t close the input, killing the pipeline, or
>> cause the rest of the data to be discarded.
> 
> I think this meets your description and complies with POSIX's dd(1p)
> here.
> 
>    $ seq 33 126 | sed 's/$/P/' | dc |
>> while :; do
>>    LC_ALL=C dd bs=10 count=1 2>dd.err | sed -n l
>>    grep -q '^[^0].* records in$' dd.err || break
>> done
>    !"#$%&'()*$
>    +,-./01234$
>    56789:;<=>$
>    ?@ABCDEFGH$
>    IJKLMNOPQR$
>    STUVWXYZ[\\$
>    ]^_`abcdef$
>    ghijklmnop$
>    qrstuvwxyz$
>    {|}~$
>    $
>    $ rm dd.err
> 
> I set the locale so the format of dd's stderr report is known.
> 
> -- 
> Cheers, Ralph.

--
Steve Jenkin, IT Systems and Design 
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