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This is probably a stupid question but I am having some trouble unmounting CD's on one of my computers.
The computer is running RedHat 7.1 and when I try to unmount a cd I get the "umount: /mnt/cdrom: device is busy" error. This is after I have killed the shell that I mounted and looked at the CD with. Fuser returns no processes using the filesystem and there is no X server running. The problem occurs everytime I try to use a CD on this particular computer.
Is there a way of umounting a file system even if it is being used? CD's are read only so there is no danger of loosing cashed write information.
it's *extremely* likely that somewhere in your system you are in the mounted directory, make sure you only have one single bash session running, and you are in your home directory and NOTHING is using the driver in any possible way. you could even drop down to single user mode (run "init 1") to make stupidly sure that you're not there at all.
Try running lsof. This will list what files are open. See if any of them are accessing the cdrom.
From man page of lsof:
An open file may be a regular file, a directory, a block special file, a character special file, an executing text reference, a library, a stream or a network file (Internet socket, NFS file or UNIX domain socket.)
Interesting command. Not one that I have run into before. Unfortunatly it produced no reference to the CD. I tried searching for mnt, cdrom and hdc (I tried hda, hdb and hdd too). Still the CD will not eject!
I had a similar problem for a while. It was the supermount option being funny. It would automagically mount the CD when I put it in the drive, and yet would not tell me that it was already mounted when I try to 'mount /mnt/cdrom'. Because it was waiting for an eject command (as opposed to an umount command), it would not let me umount it. In the end I just got rid of supermounting...
I did change the fstab but the CD was still stuck in the drive and the changes made will not have any effect untill the drive is remounted.
I rebooted the computer this morning and got the damn disk out. I then tried the drive with the changes to fstab. So far so good. I could get the disk out again! Looks like the change to the fstab has helped.