Re: standards/60663: POSIX.1-2024: dd(1) options

[Taylor R Campbell <tcplquincy20260828%campbell.mumble.net@localhost>]

> Date: Fri, 28 Aug 2026 20:18:45 +0200
> From: Martin Husemann <martin%duskware.de@localhost>
>
> You mean you could then finally do something like this?
> 
> 	zcat disk.img.gz | dd bs=1m iflags=fullblock of=/dev/rdk42
> 
> or
> 
> 	progress -zf disk.img.gz dd bs=1m iflags=fullblock of=/dev/rdk42
> 
> Sounds very usefull.

For some reason I had the idea that using ibs and obs together worked
reliably for this purpose, so I've long been doing stuff like

progress -zf disk.img.gz dd ibs=64k obs=1m of=dev/rdk42
nc ... | dd ibs=64k obs=1m of=/dev/rsd2

instead of

progress -zf disk.img.gz dd bs=1m of=dev/rdk42
nc ... | dd bs=1m of=/dev/rsd2

and while I noticed long ago that the bs=1m version didn't work
reliably, the ibs=64k obs=1m version has always appeared to work for
me.  Maybe it's an accident of coinciding with BIG_PIPE_SIZE?  Maybe
it didn't work reliably and I just wasn't verifying hard enough?  No
idea!

Anyway, yes, having this work reliably would be useful -- I dunno why
it took until 2024 for that to become a standard concept.