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I can't umount on my Linux machine and not by umount -f please advice?

[root@Linux umount /mnt/cdrom
  umount: /mnt/cdrom: device is busy
  umount: /mnt/cdrom: device is busy
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This question should probably have been asked on or since it is about using a linux system, not administering it. – Caleb Apr 13 '11 at 11:33
up vote 5 down vote accepted

You can use fuser to see which processes are still using that mount:

fuser -mu /mnt/cdrom

If you want to kill those processes via fuser, use -k:

fuser -mk /mnt/cdrom

I often (as in: I wish I had a nickel every time...) find myself unable to umount because I've cd'd to a mount as myself then su'd to root. My old shell is still on the mount point so I can't umount. Try exiting the root shell and see if your user's shell is still cd'd to something under /mnt/cdrom.

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You need to figure out what is using the tile system in the mount and stop those process. You can get an idea of what might be there by running lsof | grep /mnt/cdrom to see what procses have that folder open. You might start by closing any file managers and cd'ing out of there from any terminals.

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I dont have lsof command -:( – yael Apr 13 '11 at 11:39
Then install it or use fuser instead if you have that. – Caleb Apr 13 '11 at 11:40
Dude thank you. No fuser options would show the loop device being used but lsof worked. – bias Dec 7 '11 at 17:28

You are probably viewing the CD from a console or file browser without realising. Linux won't let you unmount it if it's in use.

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If you don't care about what may be using the device you can umount -f /mnt/cdrom which will force it to be unmounted.

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