Hi,

what does the letter »r« stand for in /dev/sr0?
(/dev/scd0 is a link to /dev/sr0.)

Regards,
Detlef Lechner

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2009/11/1 Detlef Lechner <Detlef.Lechner@gmx.net>:
> Hi,
>
> what does the letter »r« stand for in /dev/sr0?
> (/dev/scd0 is a link to /dev/sr0.)

Read-only ?

Loïc

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Detlef Lechner wrote:

> Hi,
>
> what does the letter »r« stand for in /dev/sr0?
> (/dev/scd0 is a link to /dev/sr0.)

Does it have to stand for anything? Perhaps they were just out of ideas?
It might, perhaps, be "raw", but that's just a WAG.
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Loïc Grenié wrote:
> 2009/11/1 Detlef Lechner <Detlef.Lechner@gmx.net>:
>> Hi,
>>
>> what does the letter »r« stand for in /dev/sr0?
>> (/dev/scd0 is a link to /dev/sr0.)
>
> Read-only ?

Hm.

Detlef

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Derek Broughton wrote:
> Detlef Lechner wrote:
>
>> Hi,
>>
>> what does the letter »r« stand for in /dev/sr0?
>> (/dev/scd0 is a link to /dev/sr0.)
>
> Does it have to stand for anything?

No, it does not have to. But people wuold learn and remember the name
more easily; the number of errors and mistakes would be less.

> Perhaps they were just out of ideas?

:-)

> It might, perhaps, be "raw", but that's just a WAG.

Hm, hm.

Detlef

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Detlef Lechner wrote:

> Derek Broughton wrote:
>> Detlef Lechner wrote:
>>
>>> what does the letter »r« stand for in /dev/sr0?
>>> (/dev/scd0 is a link to /dev/sr0.)
>>
>> Does it have to stand for anything?
>
> No, it does not have to. But people wuold learn and remember the name
> more easily; the number of errors and mistakes would be less.

That would be true if people really needed to know what /dev/sr0 is, but for
the most part we shouldn't need to. Once upon a time, because of some
little quirk with a Palm Pilot, I needed to know something about the
/dev/sg0 device, but when things are working properly all you should need to
know is /dev/pilot (I think - don't use it anymore!). Similarly, for most
of use, all we should need to know about the CD/DVD drive is /media/cdrom.
I'm pretty sure I've never needed to know that /dev/scd0 links to /dev/sr0,
let alone what sr0 is.
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On Tue, Nov 3, 2009 at 9:34 AM, Derek Broughton <derek@pointerstop.ca> wrote:

Detlef Lechner wrote:



> Derek Broughton wrote:

>> Detlef Lechner wrote:

>>

>>> what does the letter »r« stand for in /dev/sr0?

>>> (/dev/scd0 is a link to /dev/sr0.)

>>

>> Does it have to stand for anything?

>

> No, it does not have to. But people wuold learn and remember the name

> more easily; the number of errors and mistakes would be less.



That would be true if people really needed to know what /dev/sr0 is, but for

the most part we shouldn't need to. *Once upon a time, because of some

little quirk with a Palm Pilot, I needed to know something about the

/dev/sg0 device, but when things are working properly all you should need to

know is /dev/pilot (I think - don't use it anymore!). *Similarly, for most

of use, all we should need to know about the CD/DVD drive is /media/cdrom.

I'm pretty sure I've never needed to know that /dev/scd0 links to /dev/sr0,

let alone what sr0 is.

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derek
*Translation - I don't know either... lol
*





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Verde Denim wrote:

> On Tue, Nov 3, 2009 at 9:34 AM, Derek Broughton
> <derek@pointerstop.ca>wrote:
>
>
> Translation - I don't know either... lol

Actually, I'd already said that - and suggested "raw" as a wild guess. But
I was intrigued that Detlef thought that knowing what it stood for would
prevent errors, since I really can't imagine how most of us would need to
know it.
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On Wed, Nov 4, 2009 at 10:17 PM, Derek Broughton <derek@pointerstop.ca> wrote:

Verde Denim wrote:



> On Tue, Nov 3, 2009 at 9:34 AM, Derek Broughton

> <derek@pointerstop.ca>wrote:

>

>

> Translation - I don't know either... lol



Actually, I'd already said that - and suggested "raw" as a wild guess. *But

I was intrigued that Detlef thought that knowing what it stood for would

prevent errors, since I really can't imagine how most of us would need to

know it.

--

derek


And knowing the acronym definitions probably won't help the learning too much, either.
But, according to the Linux SCSI sub-system documentation I have, it would have to stand for _SCSI_ _READ_ since it is a cd drive that is designated read-only. For generic operations on the same device, it would map to sg0 (_SCSI_ _GENERIC_) in order to gain the write perm. Apparently all of the devices like /dev/sr0, /dev/st0, /dev/nst0x map to an sg device for generic operations.

Although _raw_ seems to be a good logical choice.

Regards

Jack

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2009/11/5 Verde Denim <tdldev@gmail.com>:
>
>
> On Wed, Nov 4, 2009 at 10:17 PM, Derek Broughton <derek@pointerstop.ca>
> wrote:
>>
>> Verde Denim wrote:
>>
>> > On Tue, Nov 3, 2009 at 9:34 AM, Derek Broughton
>> > <derek@pointerstop.ca>wrote:
>> >
>> >
>> > Translation - I don't know either... lol
>>
>> Actually, I'd already said that - and suggested "raw" as a wild guess.
>> *But
>> I was intrigued that Detlef thought that knowing what it stood for would
>> prevent errors, since I really can't imagine how most of us would need to
>> know it.
>> --
>> derek
>>
> And knowing the acronym definitions probably won't help the learning too
> much, either.
> But, according to the Linux SCSI sub-system documentation I have, it would
> have to stand for _SCSI_ _READ_ since it is a cd drive that is designated
> read-only. For generic operations on the same device, it would map to sg0
> (_SCSI_ _GENERIC_) in order to gain the write perm. Apparently all of the
> devices like /dev/sr0, /dev/st0, /dev/nst0x map to an sg device for generic
> operations.
> Although _raw_ seems to be a good logical choice.

I seriously doubt it: a "raw" device in Unix jargon, is a character device.
/dev/sr0 is a block device and a corresponding raw device would be called
/dev/rsr0, would be a character device, and it would be impossible to read
non-multiple of the sector size (2048 bytes for CDs, 512 for most hdd). I
don't remember if "raw" devices go through page cache or not (probably
not). So I strongly doubt it is a raw device.

Loïc

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