Suppose the root directory has inode number #2. Here is a small part
of a Unix file system tree, showing hypothetical inode numbers of
some directories and files:
| inode
#2 |
| . (dot) |
2 |
| .. (dot dot) |
2 |
home |
123 |
bin |
555 |
usr |
654 |
| |
|
| |
|
|
|
| inode
#555 |
| . (dot) |
555 |
| .. (dot dot) |
2 |
rm |
546 |
ls |
984 |
cp |
333 |
ln |
333 |
mv |
333 |
|
|
| inode
#123 |
| . (dot) |
123 |
| .. (dot dot) |
2 |
ian |
111 |
stud0002 |
755 |
stud0001 |
883 |
stud0003 |
221 |
| |
|
|
Note how one directory named bin (#555) has three name-to-number maps for the same
node (#333). All three names (cp,
ln, mv) refer to the same node number, in this case a file
containing an executable program. (This program is one that looks
at its name and behaves differently depending on which name you use to
call it.) |
| inode
#111 |
| . (dot) |
111 |
| .. (dot dot) |
123 |
.profile |
334 |
.login |
335 |
.logout |
433 |
| |
|
| |
|
|
|
| inode #333 |
| Disk blocks
for the
cp / ln / mv
file
(link count: 3) |
|
|
| inode #335 |
| Disk blocks
for the
.login
file
(link count: 1) |
|
Note how the inodes for files contain disk blocks for the files and the
inodes for directories contain only lists of names and inode numbers.
The data for a file is not stored with the name of the file.
The name is in the directory; the data is in the inode whose number
appears with the name in the directory.
When a directory is damaged on Unix, no file data is lost;
only the names of the files are lost.