Help with opening CD-ROM from terminal

Question

I am trying to open CD-ROM from terminal but it is showing the error;

eject: unable to find or open device for: `/dev/cdrom'

I tried to find out CD-ROM with:

sy@shiv:~$ sudo lshw -C disk
  *-disk
       description: SCSI Disk
       product: Card  Reader
       vendor: Multiple
       physical id: 0.0.0
       bus info: scsi@6:0.0.0
       logical name: /dev/sdb
       version: 1.00
       size: 3837MiB (4023MB)
       capabilities: removable
       configuration: logicalsectorsize=512 sectorsize=512
     *-medium
          physical id: 0
          logical name: /dev/sdb
          size: 3837MiB (4023MB)
          capabilities: partitioned partitioned:dos
  *-disk
       description: ATA Disk
       product: ST9500325AS
       vendor: Seagate
       physical id: 0.0.0
       bus info: scsi@1:0.0.0
       logical name: /dev/sda
       version: LVM1
       serial: S2WJMH7Q
       size: 465GiB (500GB)
       capabilities: gpt-1.00 partitioned partitioned:gpt
       configuration: ansiversion=5 guid=fbac54d6-645e-4020-9ed3-16cff0ed5c03 logicalsectorsize=512 sectorsize=512

lsblk is also not showing the CD-ROM:

sy@shiv:~$ lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sdb      8:16   1   3.8G  0 disk
└─sdb1   8:17   1   3.8G  0 part /media/sy/75E3-0CE2
sda      8:0    0 465.8G  0 disk
├─sda4   8:4    0  95.4G  0 part /
├─sda2   8:2    0   270G  0 part
├─sda3   8:3    0   3.9G  0 part [SWAP]
└─sda1   8:1    0   512M  0 part /boot/efi

Answer 1

$ sudo lshw -C disk
  *-disk                    
       …
  *-cdrom
       description: DVD-RAM writer
       product: DVDRAM GT50N
       vendor: HL-DT-ST
       physical id: 0.0.0
       bus info: scsi@1:0.0.0
       logical name: /dev/sr0
       version: LT20
       capabilities: removable audio cd-r cd-rw dvd dvd-r dvd-ram
       configuration: ansiversion=5 status=nodisc
  *-disk
       …

That's how it should look like. Your device should be named /dev/sr0 or something similar if you have more than one optical drive. /dev/cdrom and /dev/dvdrom were symbolic links to /dev/sr0, they don't have to exist and appear to not be generated anymore.

If you actually have an optical disk drive connected to the computer then it's not detected by Ubuntu and you need to investigate why. Ensure that the drive is properly connected (USB? SATA?) and that there is enough power provided to operate the drive (some USB ports and some drives don't play well). You may find hints in dmesg.

If the device is operational it should also show up in lsblk and in /dev. /dev/disk/by-path is probably the most useful representation when you're troubleshooting hardware issues.

$ lsblk 
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
…
sr0     11:0    1  1024M  0 rom  
…

$ ll /dev/disk/by-path/
total 0
drwxr-xr-x 2 root root 280 Nov 16 10:36 ./
drwxr-xr-x 8 root root 160 Nov 16 11:01 ../
lrwxrwxrwx 1 root root   9 Nov 16 11:01 pci-0000:00:1f.2-ata-1 -> ../../sda
lrwxrwxrwx 1 root root  10 Nov 16 11:01 pci-0000:00:1f.2-ata-1-part1 -> ../../sda1
lrwxrwxrwx 1 root root  10 Nov 16 11:01 pci-0000:00:1f.2-ata-1-part2 -> ../../sda2
lrwxrwxrwx 1 root root  10 Nov 16 11:01 pci-0000:00:1f.2-ata-1-part3 -> ../../sda3
lrwxrwxrwx 1 root root  10 Nov 16 11:01 pci-0000:00:1f.2-ata-1-part4 -> ../../sda4
lrwxrwxrwx 1 root root  10 Nov 16 10:25 pci-0000:00:1f.2-ata-1-part5 -> ../../sda5
lrwxrwxrwx 1 root root  10 Nov 16 10:19 pci-0000:00:1f.2-ata-1-part6 -> ../../sda6
lrwxrwxrwx 1 root root   9 Nov 27 09:10 pci-0000:00:1f.2-ata-2 -> ../../sr0
lrwxrwxrwx 1 root root   9 Nov 16 11:01 pci-0000:00:1f.2-ata-3 -> ../../sdb
lrwxrwxrwx 1 root root  10 Nov 16 11:01 pci-0000:00:1f.2-ata-3-part1 -> ../../sdb1
lrwxrwxrwx 1 root root  10 Nov 16 11:01 pci-0000:00:1f.2-ata-3-part2 -> ../../sdb2
lrwxrwxrwx 1 root root  10 Nov 16 11:01 pci-0000:00:1f.2-ata-3-part3 -> ../../sdb3