Reading from a UNIX volume..

[Alex Rice]

On Monday, August 11, 2003, at 11:21  PM, Jim Witte wrote:

>   open file "/dev/rdisk3" for binary read
>   put the result into item 1 of ret
> * read from file "/dev/rdisk3" for 4096 -- until EOF
>   put the result into item 2 of ret
>   put it into fld "rtext"
>   close file "/dev/rdisk3"
>   put the result into item 3 of ret
>
> The script as written works, but if I change the starred line to 
> 'until EOF' it doesn't - it gives a result code of 'eof' for the read 
> command.  Does EOF do strange things if the thing you're reading from 
> is a volume, and not a "real" file (whatever real means).  Is there a 
> better way to read directly from a volume other doing a file read from 
> /dev/* ?

Maybe the volume is larger than you can read in one operation, maybe 
some internal buffer size that Rev has? Try something like this
repeat ... read from file "/dev/rdisk3" at (512 * n) for 512

Or try "read from driver" instead. The docs have examples of "read from 
driver" reading from /dev files. Maybe it handles EOF differently?

OTO maybe read that's wrong and read from file is for block devices and 
read from driver is for stream devices?

Alternatively you should shell() to use dd or cp to get the data from 
the device.

Interesting question!

Alex Rice, Software Developer
Architectural Research Consultants, Inc.
http://ARCplanning.com