Re: dd: add 'skip_bytes' and 'count_bytes' operands

[Pádraig Brady]

On 02/06/2012 03:24 PM, Jérémy Compostella wrote:
>> Hmm, shouldn't there be a seek_bytes param too for consistency?
> That was effectively my first mail question. As you talk about it in
> your explanation addition in coreutils.texi I guess I should start
> implementing it ?

I think so.

Note it annoys me to be adding 3 new options to dd,
though I can't think of how to simplify off hand.
Anyway if we do think of a better way it will probably only
involve minor interface code changes.

>> This additional doc change is necessary I think:
>> --- a/doc/coreutils.texi
>> +++ b/doc/coreutils.texi
>> @@ -8354,8 +8354,10 @@ should not be too large---values larger than a few 
>> megabytes
>>  are generally wasteful or (as in the gigabyte..exabyte case) downright
>>  counterproductive or error-inducing.
>>
>> -Use different @command{dd} invocations to use different block sizes for
>> -skipping and I/O@.  For example, the following shell commands copy data
>> +To use different block sizes for skipping and I/O@
>> +you can use the @samp{skip_bytes} and @samp{seek_bytes} options,
>> +or the traditional method of separate @command{dd} invocations.
>> +For example, the following shell commands copy data
>>  in 512 KiB blocks between a disk and a tape, but do not save or restore a
>>  4 KiB label at the start of the disk:
> OK. I would add something about count_bytes too, no ?

Well this example was just about skipping,
but it's probably best to mention all related args there.
How about:

"
To process data that is at an offset or size that is not a
multiple of the I/O@ block size, you can use the @samp{skip_bytes},
@samp{seek_bytes} and @samp{count_bytes} options.  Alternatively
the traditional method of separate @command{dd} invocations can be used.
For example, the following shell commands copy data
"

> Should I import your patch suggestions in my patch or do you will make
> an additional commit on top of it ? That's particularly relevant if I
> implement the seek_bytes operand.

It's best if we can --amend everything into your patch.

cheers,
Pádraig.