Page 153 - DCAP403_Operating System

Operating System

Notes Single Level Directory

In single level directory all files are contained in the same directory. It is easy to support and

understand. It has some limitations like:

1. Large number of files (naming).
2. Ability to support different users/topics (grouping).

Figure 8.2: Single Level Directory
directory cat bo a test data mail cont hex records

files

Two Level Directory

In two level directory structure one is master file directory and the other is user fi le directory.
Here each user has their own user file directory. Each entry in the master file directory points to a

user file directory. Each user has rights to access their own directory but can’t access other user’s

directory, if permission is not given by the owner of the second one.
Figure 8.3: Two Level Directory
master
file user 1 user 2 user 3 user 4
directory

user file
directory cat bo a test a data a test x data a

Three Level Directory

In three level directory the directory structure is a tree with arbitrary height. Here users may
create their own subdirectories.
Figure 8.4: Three Level Directory

spell bin programs

stat mail dist find count hex recorder p e mail

prog copy prt exp recorder list find hex count

list obj spell all last first

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