How to detect the CD in the CD-ROM is a:
CD?
CD-R?
CD-RW?
DVD?
DVD-R?
DVD-RW?
or something else?

Thanks.

Not sure about specifics from one software to the next, but the drive itself tends to know what's inside itself, to a point.
type 'hdparm' for the help page. There you will see hdparm options which can be applied to the drive. One of them, I think it's a -I will return all info that the drive has about itself in general, including the type of disk to the best of its knowledge in some drives.
Perhaps using grep or cat on the results of hdparm -I /dev/hd? to isolate the disk type is what you are looking for?
There may be another way, but this came to mind first.

Thank you GrapefruiTgirl, i typed this command, but there is no such command.
By the way, i'm using Fedora Core 3 at this moment.

Oops, I should have mentioned, if your system does not have hdparm, you can get it from Sourceforge.net, or just google it
Sorry for the inconvenience.

That's Ok.

Actually, I'm writing a program that will only write data on a Blank CD-R, unless there is a way to make the CR-RW to be CD-R after writing.

That's why i need to detect the type of the CD.

Once a CDRW is finalised, it technically becomes a CD-R. However, as I understand it, they can still be ERASED, and made into a CDRW again, until their maximum usage has been reached, which is around 1000 writes.

Exactly, but what i need to do is to ensure the CD is a CD-R, so the data i wrote on that CD is unchangeable for some security reason.

somebody suggested:

media_type="unknown-media"
infotext=$(cdrecord dev=$scsi_adr -atip 2>&1)
if echo "$infotext" | \
grep 'book type:.*DVD+RW' >/dev/null 2>&1
then
media_type="DVD+RW"
elif echo "$infotext" | \
grep 'book type:.*DVD-RW' >/dev/null 2>&1
then
media_type="DVD-RW"
elif echo "$infotext" | \
grep 'book type:.*DVD+R' >/dev/null 2>&1
then
media_type="DVD+R"
elif echo "$infotext" | \
grep 'book type:.*DVD-R' >/dev/null 2>&1
then
media_type="DVD-R"
elif echo "$infotext" | \
grep '^ Is erasable' >/dev/null 2>&1
then
media_type="CD-RW"
elif echo "$infotext" | \
grep '^ Is not erasable' >/dev/null 2>&1
then
media_type="CD-R"
fi
echo "Detected media type : $media_type"

But i'm not familar with shell script, so i haven't found out if this work.