[COFF] Shell script advice: using 'dd' to write multiple media
Adam Thornton
athornton at gmail.com
Tue Jun 27 16:28:24 AEST 2023
My approach would have been to use "split" on the original file and then dd
the resulting files. But now I find myself wondering how old "split" is.
It was certainly already a well-established thing by the early 90s.
On Mon, Jun 26, 2023 at 11:23 PM Ralph Corderoy <ralph at 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.
>
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