I booted knoppix with 3 cd r/w hoping to be able to
use dd if=/dev/cdrom1 of=/dev/cdrom2. The desktop
shows these devices but the root shell says /mnt/cdrom2
is a symbolic link to nowhere.

Dmesg gives this
scsi0 : SCSI host adapter emulation for IDE ATAPI devices
Vendor: LITE-ON Model: COMBO SOHC-5232K Rev: NK05
Type: CD-ROM ANSI SCSI revision: 02
Vendor: HP Model: CD-Writer+ 9100 Rev: 1.0c
Type: CD-ROM ANSI SCSI revision: 02
Vendor: MATSHITA Model: DVD-RAM UJ-815A Rev: D100
Type: CD-ROM ANSI SCSI revision: 02
Attached scsi CD-ROM sr0 at scsi0, channel 0, id 0, lun 0
Attached scsi CD-ROM sr1 at scsi0, channel 0, id 1, lun 0
Attached scsi CD-ROM sr2 at scsi0, channel 0, id 2, lun 0
sr0: scsi3-mmc drive: 24x/52x writer cd/rw xa/form2 cdda tray
Uniform CD-ROM driver Revision: 3.12
sr1: scsi3-mmc drive: 32x/32x writer cd/rw xa/form2 cdda tray
sr2: scsi3-mmc drive: 24x/24x writer dvd-ram cd/rw xa/form2 cdda caddy

The hd is revealed by
df /dev/sr2
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sr2 1971 1445 526 74%

There is a blank cd in cdrom2 and dmesg gives this error
I/O error: dev 0b:02, sector 0
VFS: Can't find ext3 filesystem on dev sr(11,1).
VFS: Can't find ext2 filesystem on dev sr(11,1).
ISO 9660 Extensions: Microsoft Joliet Level 3
ISO 9660 Extensions: RRIP_1991A

Can anyone tell me why this happens or what I can do to make this
work? I don't want to buy anoter hd to make this copy.
Thanks,
suguru

Not sure if you can copy cds with dd, try cdrecord.

did you try

dd if=/dev/cdrom of=imagename.iso

then burn the .iso with cdrecord or via a frontend like XCDRoast