Re: Detect CD Media Type?

[scdbackup@gmx.net]

boo0330:
>>> Now I can detect CD-R, CD-RW very well by -atip
>>> but are there information about the CD-R is closed, or it's blank, can
>>> write or not?
me:
>> I can distinguish them by this shell code snippet which does a 1 byte
>> test read :
>>   if dd if=/dev/sr0 of=/dev/null bs=1 count=1
>>   then echo "Has data" ; else ; echo "Seems to be empty" ; fi
Jörg:
> This does not work correctly in all cases.
> Use the "official" way and call readcd sectors=0-0

readcd is very appealing for that purpose because it uses 
the same addresses as cdrecord.

I read in man readcd :
"... so  sectors=0-0
 will not read anything and may be used to check for
 a CD in the drive."

I read further and tried this shell snippet :
 if readcd dev=0,0,0 sectors=0-0 f=- >/dev/null 2>&1 
 then 
   echo success
 else
   echo failure
 fi
As announced by the manual it does react on a blank CD-R with the
same exit value as on a CD-R which carries a closed session.

There is a difference visible in one of the stderr output lines,
though.
Blank CD-R :
  Capacity: 1 Blocks = 2 kBytes = 0 MBytes = 0 prMB
Written CD-R :
  Capacity: 126018 Blocks = 252036 kBytes = 246 MBytes = 258 prMB

Did i miss any better trick here ?

Additionally the question is still open about how to see wether a
CD-R(W) is finally closed or wether it is still appendable.


Have a nice day :)

Thomas