TLS: iMac, cdrom, and the eject key

Aluminum iMac with disc ejectedEditor’s Note: This article is part of the Tales of A Linux Switcher series.

As part of my on-going switch to Ubuntu 12.04 from Mac OS X, I ran into an issue where my cdrom device was not being mapped properly in the OS.

Everything works as desired except for one little thing: the eject key on the Apple Aluminum USB keyboard was not triggering the eject sequence of the built-in slot loading SuperDrive.

I assumed that there would be a device mapped to the actual drive using a link to /dev/cdrom.  This didn’t turn out to be the case.  When using the eject command from a terminal I received the following:

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

When I did a directory list to find any applicable cdrom device entries in the udev root (/dev) I got the following:

$ udevadm info --root
root@foreandy-iMac:~# ls -l /dev/*cd*
ls: cannot access /dev/*cd*: No such file or directory

In order to determine exactly which device was being used for the optical drive, I looked at the output from system’s cdrom device entry:

$ cat /proc/sys/dev/cdrom/info
CD-ROM information, Id: cdrom.c 3.20 2003/12/17

drive name: sr0
drive speed: 24
drive # of slots: 1
Can close tray: 1
Can open tray: 1
Can lock tray: 1
Can change speed: 1
Can select disk: 0
Can read multisession: 1
Can read MCN: 1
Reports media changed: 1
Can play audio: 1
Can write CD-R: 1
Can write CD-RW: 1
Can read DVD: 1
Can write DVD-R: 1
Can write DVD-RAM: 0
Can read MRW: 0
Can write MRW: 0
Can write RAM: 1

The next step was to create the symbolic link in the device root to map cdrom to the appropriate device as listed in the above output:

$ sudo ln -s /dev/sr0 /dev/cdrom
$ ls -l /dev/*cd*
lrwxrwxrwx 1 root root 8 Jul 30 09:58 /dev/cdrom -> /dev/sr0

Now I can use both command line utilities to work with the optical drive as well as the built-in eject key on my keyboard.

If you want a lot more detail on this issue check out this bug comment.  While not specifically dealing with a Mac, the issues and solution are the same.