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

["Robert Elz via gnats" <gnats-admin%NetBSD.org@localhost>]

The following reply was made to PR standards/60663; it has been noted by GNATS.

From: Robert Elz <kre%munnari.OZ.AU@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: standards/60663: POSIX.1-2024: dd(1) options
Date: Sat, 29 Aug 2026 06:06:25 +0700

 I am waiting for an (absurdly slow) "cvs update" to complete, so
 I can do a build to verify I am not likely to be breaking anything,
 but in the meantime this is what the changes cause:
 
 jacaranda$ cat /netbsd | ./dd iflags=fullblock bs=128k of=/tmp/TRASH
 207+1 records in
 207+1 records out
 27214200 bytes transferred in 0.040 secs (680355000 bytes/sec)
 
 jacaranda$ cat /netbsd | ./dd bs=128k of=/tmp/TRASH
 0+1662 records in
 0+1662 records out
 27214200 bytes transferred in 0.048 secs (566962500 bytes/sec)
 
 I wouldn't place much emphasis on the bytes/sec differences, these were
 singleton runs, the difference is that with "iflags=fullblock" each block
 read is 128k whereas without it, they aren't, which would have affected
 count=10 or something, had I specified it.
 
 Similarly:
 
 jacaranda$ cat /netbsd | ./dd iflags=fullblock ibs=128k obs=256k of=/tmp/TRASH
 207+1 records in
 103+1 records out
 27214200 bytes transferred in 0.058 secs (469210344 bytes/sec)
 
 jacaranda$ cat /netbsd | ./dd ibs=128k obs=256k of=/tmp/TRASH
 0+1662 records in
 103+1 records out
 27214200 bytes transferred in 0.051 secs (533611764 bytes/sec)
 
 kre
 
 ps: cvs finished its update while I have been typing, so commit should be soon.