Problem with dd and /dev/sr0

[Rick Stevens]

On 03/14/2016 10:11 AM, jd1008 wrote:
> Hi all,
> time dd if=/dev/sr0 of=Our_Group_Picnic.iso bs=64M skip=5888
> conv=noerror,notrunc oflag=append
> dd: ‘/dev/sr0’: cannot skip: Invalid argument
> 0+0 records in
> 0+0 records out
> 0 bytes (0 B) copied, 0.000301689 s, 0.0 kB/s
>
> but
>
> {3464-jd at localhost}$ time dd if=/dev/sr0 of=Our_Group_Picnic.iso bs=64M
> conv=noerror,notrunc
>
> works just fine.
>
> So why is it that skip des not work on optical media?

Skip works fine, but you must specify the units. "skip=5888" doesn't
tell dd how far to skip. E.g. "skip=5888c" would skip 5888 bytes. From
the man page:

	N and BYTES may be followed by the following multiplicative
	suffixes: c=1, w=2, b=512, kB =1000, K=1024, MB=1000*1000,
	M=1024*1024, xM=M  GB=1000*1000*1000, G=1024*1024*1024, and
	so on for T, P, E, Z, Y.

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- Rick Stevens, Systems Engineer, AllDigital    ricks at alldigital.com -
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