UUID

1. If you don't know the UUID of your disk, you can find it by using one of the several commands below:

host # vol_id /dev/sda3
...
ID_FS_UUID=a1331d73-d640-4bac-97b4-cf33a375ae5b
...

or:

host # blkid /dev/sda3 <-- Leave blank to show all disks
/dev/sda3: LABEL="/" UUID="a1331d73-d640-4bac-97b4-cf33a375ae5b" SEC_TYPE="ext3" TYPE="ext2"

also:

host # ls -l /dev/disk/by-uuid|grep sda3
lrwxrwxrwx 1 root root 10 11. Okt 18:02 a1331d73-d640-4bac-97b4-cf33a375ae5b-> ../../sda3

2. If you prefer to generate your own UUID's (see above), you can use the uuidgen command and couple it with tune2fs to change the default UUID assigned to your disk by the system, like this:

host # uuidgen
1d721189-7b71-4315-95a7-1c3abc90d379
host # tune2fs -U 1d721189-7b71-4315-95a7-1c3abc90d379 /dev/sda3

3. Then again, if you already know the UUID, you might want to find out what disk it's associated with. You can generally get this information with the "findfs" command, like so:

host # findfs UUID=a1331d73-d640-4bac-97b4-cf33a375ae5b
/dev/sda3

Of course, using some of the commands above and grepping out part of the UUID will also get you your answer, like:

host # ls -l /dev/disk/by-uuid|grep a1331d73-d640-4bac-97b4-cf33a375ae5b
lrwxrwxrwx 1 root root 10 11. Okt 18:02 a1331d73-d640-4bac-97b4-cf33a375ae5b-> ../../sda3

or

host # blkid|grep a1331d73-d640-4bac-97b4-cf33a375ae5b <-- remember that blkid with no arguments returns all of the system disk
/dev/sda3: LABEL="/" UUID="a1331d73-d640-4bac-97b4-cf33a375ae5b" SEC_TYPE="ext3" TYPE="ext2"

4. And, lastly (for this post, at least ;), you can mount your disks using the UUID, and even incorporate that automated UUID mounting into your /etc/fstab. To mount directly from the command line, you can do something like this:

host # mount -U a1331d73-d640-4bac-97b4-cf33a375ae5b /directory/you/mount/this/disk/on

and you could instruct your system to mount this partition by UUID from within the fstab, as well. It works basically the same way that the LABEL keyword does:

host # cat /etc/fstab
...
UUID=a1331d73-d640-4bac-97b4-cf33a375ae5b /directory/you/mount/this/disk/on ext3fs defaults 1 1


And, at this point, you should be able to figure your way around using UUID's to manipulate your disk on Linux with no problem. Enjoy, and please "be careful" :)