I am a bit behind the power curve when comes to all the various types of media. So please excuse my ignornace. Aren't CD's (even CD/RW CD's) only write once? I mean even if I could figure out how to write to a CD a second time or delete data from a CD wouldn't the capacity of the CD be diminished.

How can I write to this CD ...

Here's a df -H. It shows that I have a cd mounted. I previously wrote the 2nd volumn of a mkCDrec full backup to it.

bash-2.05b$ df -H
Filesystem Size Used Avail Use% Mounted on
/dev/hda2 39GB 3.7GB 34GB 11% /
/dev/hda1 104MB 9.6MB 89MB 10% /boot
none 127MB 0 127MB 0% /dev/shm
/dev/cdrom 111MB 111MB 0 100% /mnt/cdrom

bash-2.05b$ ls -l /mnt/cdrom
total 108202
-r--r--r-- 1 root root 0 Jun 29 12:41 CDrec-29.06.2004_2
-r--r--r-- 1 root root 199 Jun 29 12:41 Checksums.md5
-r--r--r-- 1 root root 639265 Jun 29 12:41 hda2._.log.gz
-r--r--r-- 1 root root 110158740 Jun 29 12:41 hda2._.tar.gz
-r--r--r-- 1 root root 0 Jun 29 12:41 LAST_CD

I will attempt to write some more data to this CD. I'll create ISO 9660 filesystem file and
then attempt to write it to the CD with cdrecord.

[root@localhost dogfacemonkey]# mkisofs -o notes.iso -R -A -V NOTES
Using MKCDR000.HTM;1 for NOTES/MKCDREC/mkCDrec_RH9_restore_test.html (mkCDrec_RH9_install.html)
Using MKCDR001.HTM;1 for NOTES/MKCDREC/mkCDrec_RH9_install.html (mkCDrec_RH9_backup.html)
Using MKCDR000.XML;1 for NOTES/MKCDREC/mkCDrec_RH9_restore_test.xml (mkCDrec_RH9_install.xml)
Using MKCDR001.XML;1 for NOTES/MKCDREC/mkCDrec_RH9_install.xml (mkCDrec_RH9_backup.xml)
Total translation table size: 0
Total rockridge attributes bytes: 7860
Total directory bytes: 30720
Path table size(bytes): 214
Max brk space used e024
272 extents written (0 Mb)

[root@localhost dogfacemonkey]# ls -l notes.iso
-rw-r--r-- 1 root root 557056 Jul 7 09:46 notes.iso

[root@localhost dogfacemonkey]# cdrecord -v -eject dev=0,0,0 notes.iso
Cdrecord 2.0 (i686-pc-linux-gnu) Copyright (C) 1995-2002 J?rg Schilling
TOC Type: 1 = CD-ROM
scsidev: '0,0,0'
scsibus: 0 target: 0 lun: 0
Linux sg driver version: 3.1.24
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
bailing out..

It doesn't work. Why?

Maybe I need to "blank" the CD ...

[root@localhost dogfacemonkey]# cdrecord blank=all
Cdrecord 2.0 (i686-pc-linux-gnu) Copyright (C) 1995-2002 J?rg Schilling
scsidev: '1,5,0'
scsibus: 1 target: 5 lun: 0
Linux sg driver version: 3.1.24
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
bailing out..
[root@localhost dogfacemonkey]# cdrecord dev=0,0,0 blank=all
Cdrecord 2.0 (i686-pc-linux-gnu) Copyright (C) 1995-2002 J?rg Schilling
scsidev: '0,0,0'
scsibus: 0 target: 0 lun: 0
Linux sg driver version: 3.1.24
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
Error trying to open /dev/scd0 exclusively ... retrying in 1 second.
bailing out..

Well that didn't work either!

What the story with CD/RW. Is it still a write once world?

A blank CD-R is "write once, read many times", while in contrast a blank CD-RW can be written to multiple times. And No, subsequent overwriting of a CD-RW will not diminish its storage capacity.

In short, if you are interested in being able to erase and rewrite data on a CD, you need to be using a CD-RW. Personally, when it comes to CD-RW's, I think you get what you pay for, and therefore I would advise going with a well known brand (such as TDK, Maxell, etc) rather than a no-name generic brand. -- J.W.

Thanks for your reply J.W.!

Okay so I overwrite data on a CD-RW. How do I do it?

I think I have a CD-RW drive ....

bash-2.05b$ cdrecord dev=0,0,0 --scanbus
Cdrecord 2.0 (i686-pc-linux-gnu) Copyright (C) 1995-2002 J?rg Schilling
scsidev: '0,0,0'
scsibus: 0 target: 0 lun: 0
Linux sg driver version: 3.1.24
Using libscg version 'schily-0.7'
cdrecord: Warning: using inofficial libscg transport code version (schily - Red Hat-scsi-linux-sg.c-1.75-RH '@(#)scsi-linux-sg.c 1.75 02/10/21 Copyright 1997 J. Schilling').
scsibus0:
0,0,0 0) 'SONY ' 'CD-RW CRX216E ' 'PD01' Removable CD-ROM
0,1,0 1) *
0,2,0 2) *
0,3,0 3) *
0,4,0 4) *
0,5,0 5) *
0,6,0 6) *
0,7,0 7) *

... and my media says "CD-ReWritable" on it. So I should be able to add files to the CD right? If so how do I do that? Can I use cdrecord? Can I add ISO 9660 filesystem files to the CD?

Thanks!

Just to clarify. With CD-RW media, you record it like you would a cd-r until it gets full. Then if in the future you don't need the data, you erase the _entire_ disk. Return it to the original blank state. I don't know how you do that on the command though I'm sure it's possible. Most gui cd burning software has an erase util.

With cd-r's dirt cheap in bulk, I don't see the point myself. But in theory you can save money.

Hi

use the following to erase entire cd

cdrecord -v -eject dev=/dev/sg0 speed=24 blank=all

also man cdrecord will give many more options
cheers

According to your system listing, Yes, you've got a Sony CD-RW, so you should be able to do this pretty easily. And just to add one comment to what synapse posted: naturally the speed parameter and device name may need to be adjusted to fit your specific machine. -- J.W.