12/24/20

File management

 

Operating System

 

5. FILE MANAGEMENT

A generalization of file services.

Directory structure, command Language uses view of the file System

File management system: -

1. The process of manipulating files in computer system is known as file management which includes the process of creating, modifying and deleting the files.

2. A file management system is used for file maintenance operations; it is a type of software that manages data files in a computer system.

3. File management system is also known as file manager.

4. It has limited capabilities and it is designed to manage individual or group files like special office documents and records.

5. Some more advanced file management systems can provide additional functions like Document Management Software (DMS) which can organize important documents.

6. A file management system should not be confused with a file system which manages all type of data and files in an operating system or Database Management System (DBMS) which has relational database capability and include programming language for further data manipulation.

7. The default file management system of Microsoft Windows operating system is Windows Explorer. On the other hand Mac computers file management it is taken belongs to a tool called Finder.

The following task performed by the file management of operating system of any computer system.

1.   File management system helps to create new files in our computer system and placing them at specific locations.

2.   By the help of file management we can easily and quickly locate files in our computer system.

3.   The process of sharing of the files among different users is very easy and user friendly.

4.   It helps to store files in separate folder which is known as directories which help user to search file quickly e out to manage the files according to their types or uses.

5.   The user can easily modify the data of files and the name of the file in the directories.

The file management function in operating system is based on the following concepts: -

1.   File attributes: -

File attributes specifies the characteristics of the file such as type date of last modification size location on this sector it help the user to understand the value and location of files.

2.   File operations: -

It specifies the task that can be formed on a file such as opening and closing of file.

3.   File access permission: -

The access permission related to a file such as read or writes.

4.   File systems: -

The logical method of file storage in a computer system some of the commonly used file system include FAT and NTFS.

File (A generalization of file services): -

1.   One of the most basic and important features of operating system is file management.

2.   Files of computer system are managed by operating system.

3.   A file is collections of related information that are stored are recorded on secondary storage such as magnetic disks, magnetic tapes and optical disks.

4.   It can be defined as a data structure which stores the sequence of records.

5.    Files are stored in system which may exist on a disk or in the main memory.

6.   Files can be e a simple text or in complex form that is specially formatted.

Attribute of the file: -

1. Name: -

Each file carries a name by which the file is recognized in the file system.

2. Identifier: -

File has its own extension which identifies the type of the file for example a text file has the extension .txt a video file can have the extension .MP4.

3. Type: -

The files are classified in different type suggest video files audio file to text file executable files except.

4. Location: -

There are several location on which the file can be stored is file carries its location as its attribute.

5. Protection: -

The head of the computer may want the different protection in the different files therefore each file carries its own set of permission to different group of users.

6. Time and Date: -

File carries a time stamp which contains the time and date on which the file is last modified.

 

 

Directory structure: -

1.   File directory is a collection of file.

2.   This contains the information about files including files attribute location of the file and ownership.

3.   This information is especially that is concerned with storage, is managed by the operating system.

4.   The directory is itself a file which is accessible by various file management routines.

5.   Directory is the listing of the related files on the disk and it is a type of container that is used to contain folders and files.

Operations performed in directories are: -

a.   Creation of a file

b.   Searching for a file

c.   Deleting a file

d.   List a directory

e.   Rename a file

f.   Traverse the file system

Advantages of maintaining a directory is: -

       1.   Efficiency- File can be located more quickly

       2.   Naming- It becomes difficult for user as to two files having same name for different item

    3.   Grouping- Grouping of Piles can be done by properties exam per all are Java programs, all games etc.

There are several logical structures of directories as follows: -

1. Single-level directory: -

a. Single level directory is simplest directory structure all files in it are contained in same directory which make it easy to support and understand.

b. A single level directory has significant limitations, when the number of files increase or when the system has more than one source.

c. All the files are in the same directory they must have the unique name if two user’s call their data set test then the unique name rule is violated.

                                        (Click on image for better view)

Advantages: -

1. It is a single directory so its implementation is very easy.

2. Searching will become faster if the sizes of files are smaller.

3. The operations like creation of file searching a file deletion updating are very easy in such a directory structure.

Disadvantages: -

1. If the directory is large in size searching will become time taken

2. It cannot group the same type of files together.

3. There are many chance of name collagen due to two files cannot have the same name.

 

        2. Two-Level Directory: -

a. Two level directories cover the disadvantages of single level directory like confusion of files names among different users.

b. Two level directory structures provide to each user their own user file directory (UFD).

c. The user file directory (UFD) has similar structures but each list only the files of a single user

d. The master file directory (MFD) is indexed by username or account number and each entry points to the user files directory (UFD) for that user.

                            (Click on image for better view)

Advantages: -

1. By using two level directories we can give full path like user name, directory name.

2. Different users can have same directory as well as same file name.

3. Due to path name and user grouping files can be searched more easily.

          Disadvantages: -

1. Users can not allow sharing files with other users.

2. Two files of the same type cannot be grouped together in the same user.

 

3. Tree- Structured Directory: -

a. Tree structure directory is maintained in the form of a tree.

b. The natural generalization of a structured directory is to extend the directory structure to a tree of arbitrary height.

c. This generalization allows the user to create their own subdirectories and to organize their own files accordingly.

d. A tree structure is the most common directory structure where it has a root directory and every file in the system have a unique path.

                                        (Click on image for better view)

Advantages: -

1. It is very generalize and full part name can be given.

2. The probability of name collagen in this structure is very less.

3. Searching become very easy E and we can use both absolute path as well as relative path.

Disadvantages: -

1. Every file does not fit into the hierarchical model therefore files may be saved into multiple directories.

2. Sharing of files is not possible.

3. It is in-efficient because accessing a file may go under multiple directories.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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