Same inode numbers?

[Prasad Joshi]

Hi All,

I am printing the inode numbers of directories which are mounted under /mnt/

bash-2.02# ls -i /mnt/
136712 vol 2 vset1 2 vset2 2 vset3 2 vset4

As can be seen all vset1 to vset4 have same inode numbers.

Can any one explain?

Thanks a lot.
Prasad

[Warren_9]

hi,

it can happen if the file are hard link.

# cd /test
# touch hehe
# ln hehe haha
# ls -i
21 ren 21 war

GOOD LUCK!!

[Arunvijai_4]

Hi Prasad,

It happens only when you have hard links on /mnt. Check ll /mnt to find it out.

Also, take a look at http://en.wikipedia.org/wiki/Inode for a detailed explanation about inode.

-Arun

[Senthil Kumar .A_1 · Accepted solution]

Hi Prasad,

In the following case, it is a special case not a hard link per say. If you notice though the inodes are identical , the value is 2. It means, it is a directory on which a filesystem is mounted. Thats because the root inode of any filesystem is "2". If you unmount the filesystems on these vset* directories and run the same command again, you will notice that the inodes will not be identical anymore.

To know more about this internal concept I recommend you to go through a book titled...

The design of the UNIX operating system - Maurice J. Bach

regards,
Senthil Kumar .A

[Prasad Joshi]

Those are not surely hard links.
As you can see from this output

bash-2.02# ls -li
total 8
136712 drwxr-xr-x 2 root root 96 Apr 27 17:28 vol
2 drwxrwxrwx 6 root root 1024 May 3 13:23 vset1
2 drwxrwxrwx 5 root root 1024 Apr 27 17:34 vset2
2 drwxrwxrwx 5 root root 1024 Apr 27 17:34 vset3
2 drwxrwxrwx 5 root root 1024 Apr 27 17:34 vset4

[Senthil Kumar .A_1]

Hi,

Just for confirmation, can you see the output of the command, "bdf" or "df -k" and see whether thay are mountpoints or not ?

Regards,
Senthil Kumar .A

[Prasad Joshi]

Ya they are mount points only.

I checked with the BACH. It is a valid behavior.

Thanks a lot for your help.

[Andrew Merritt_2]

Just to make one point clear, as I don't see it stated above, inode numbers are only unique within a file system. As there are several filesystems mounted in the same directory that's why the inode number can be duplicated, and it's part of the design that the root inode has the value 2.

Andrew