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

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

Apropos the ESIX SVR4 distro on floppies or streaming tape mentioned by Bill Corcoran

	<https://www.tuhs.org/mailman3/hyperkitty/list/coff@tuhs.org/message/WEJQQCJHH7BVVRGR4QNLS4AQ2OCAJRU7/>

In the mid 1980’s I worked for a small Australian outfit that did “Unix”.

One of the things we did was distributing software, which required writing to many media.

There was a very clever script that broke the distribution into many parts, if needed,
to suit the size of the distribution media. [ tape, 3.5” floppy, 2.5” floppy, etc ]

Over the years I’ve tried to recreate a version and not succeeded :(

There was a ‘create the distro’ step of the pipeline which gathered the input,
followed by a loop that used ‘dd’ to block the stream into media-sized parts.

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.

The script let our admin staff reliably create distros on whatever media was requested.

Any suggestions or hints?
I’m thinking this is obvious, but in the man pages i’ve read, not found an answer.

It could be modern versions of ‘dd’ don’t have this behaviour.

cheers
steve

--
Steve Jenkin, IT Systems and Design 
0412 786 915 (+61 412 786 915)
PO Box 38, Kippax ACT 2615, AUSTRALIA

mailto:sjenkin@canb.auug.org.au http://members.tip.net.au/~sjenkin