I don't remember where this scrible came from. I've
had it for a while (rh5.2?).
Files are identified by the system by thier inode number, which is a unique
file system identifier for the file.
The following will display the inode numbers and corresponding files in
a directory.
$ ls -i
A directory listing is actually a listing of inode numbers with thier corresponding
filenames.
Each filename has a link to a particular inode.
You can have more than one filename pointing to the same inode.
Hard links
Two completely different filenames pointing to the same inode. If you
modify one, you are modifing both. If you delete one, the other is
still there. Hard links must be on the same filesystem.
Symbolic links
Does not link the file by inode. Links by filename. must use
across different partitions.
File permission on a symbolic link are detemined by the target file.
Example:
lets say you have two partitions. one mounted on / and the other mounted
on /usr. (remember this is just an example)
Now you want to add a directory off / called opt but there is not enough
space on / to add the file you want.
We can create a directory in /usr, which has lots of free space ;-), called
/usr/opt. The problem is we want it to look like it is accually in
the root partition(/opt) So we can make a symbolic link from /opt to
/usr/opt. When someone does a "cd /opt" they will actually go to /usr/opt.
Cool that is what we want.
First create the real directory.
# mkdir /usr/opt
Now link /opt to /usr/opt
# ln -s /usr/opt /opt
you should be ready to use /opt now.