On Tue, 19 Jun 2001, Peter Jay Salzman wrote:
> begin: Mister Resistor <[EMAIL PROTECTED]> quote
> >
> > > also, a question about dd. according to the man page, bs=BYTE tells dd to
> > > read and write BYTE bytes. count=BLOCK tells dd to copy only BLOCK input
> > > blocks.
> > >
> > > what is a block?
> >
> > Probably the equivalent of a sector. Read the man pages. :-)
>
> i'd be glad to if you could tell me which man page to read... :)
That would be nice, but it is in
man dd
if you interpolate:
---Quote---
count=BLOCKS
copy only BLOCKS input blocks
ibs=BYTES
read BYTES bytes at a time
[...]
obs=BYTES
write BYTES bytes at a time
[...]
seek=BLOCKS
skip BLOCKS obs-sized blocks at start of output
skip=BLOCKS
skip BLOCKS ibs-sized blocks at start of input
-----------
<hypothesizing>There is something historical about dd that I never quite
understood. It was described to me as a tool for converting data from
storage on one type of device to storage on another, with 9-track tapes
from various sources being common examples at the time it was described to
me. Of course, I have only used a 9-track tape once, and that was on a
VMS system, so I don't know much about them. I imagine that if a device
driver could only support certain block sizes, a tool like dd would be
useful for extracting data from tapes with an odd block size and putting
it on tapes with a size more to your liking. I don't know if such
restrictions remain in modern device drivers...</hypothesizing>
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