Directories

Question 1

What is the problem with duplicating file information when shared files are required?

Answer 1

It is difficult to maintain consistency if either file is modified. Only suitable for read-only files

Question 2

What is the difference between a hard link and a soft link?

Answer 2

Hard links point to the actual file inode or FCB. Soft links just point to another hard link.

Question 3

What happens when the file pointed to by a symbolic link is deleted?

Answer 3

The soft link points to nothing. Errors are generated when trying to open it. Think shortcuts in Windows OS.

Question 4

What happens when hard links are deleted?

Answer 4

The file reference count in the file inode is decremented. If it was the last hard link, then the entire file is deleted.

Question 5

What is a single-level directory?

Answer 5

All files are kept in the same space

Question 6

What are problems with single-level directory?

Answer 6

Unique filenames. Large number of files difficult to search, or organise.

Question 7

What is a multi-level directory structure?

Answer 7

Each user gets their own User File Directory (UFD) which are located in the Master File Directory (MFD)

Question 8

Benefit with UFDs?

Answer 8

Users can have duplicate filenames between each other.

Still no sharing, or subdirectories.

Question 9

Why doesn’t UNIX allow directory hard links?

Answer 9

They will introduce cycles in file system tree, causing infinite recursion during traversal.

UNIX only allows symbolic links to directories.