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Table of contents
1.
Introduction
2.
What is a file?
3.
File Attributes
4.
File Creation and Manipulation
5.
File Organization and Search
6.
File Security and Metadata
7.
File Compression and Encryption
8.
Frequently Asked Questions
8.1.
What is a system call?
8.2.
What is a file?
8.3.
What are the file operations?
9.
Conclusion
Last Updated: Apr 18, 2024
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File Systems in Operating System

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Introduction

File handling is one of the major topics in programming and is very useful in accessing, and modifying the files from a program. In this blog, we will be taking a brief look at all the necessary and helpful functions that we can utilize for handling files in our programs. But before that, let us take a look at what file is. 

Compiler Design

You can also read about the Multilevel Feedback Queue Scheduling and Data Structure

What is a file?

A file is a collection of related data stored on the secondary storage in a sequence of operations. The creator who creates the file defines the content of the files.

Operations on file (or file operations ):

The various operations can be performed on a file like reading, writing, opening, closing, etc. These operations are called file operations. The user performs file operations with the help of commands provided by the operating system.

Some common operations on file are:

Create operation, open operation, write operation, read operation, reposition operation, delete operation, truncate operation, close operation, append operation, rename operation.

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File Attributes

  • File Type: Indicates the type of file, such as text, image, executable, etc.
  • File Name: The name assigned to the file by the user or system.
  • File Size: The size of the file in bytes or other units.
  • File Extension: The characters after the last dot in the file name, indicating the file type.
  • Creation Date: The date and time when the file was created.
  • Modification Date: The date and time when the file was last modified.
  • Access Date: The date and time when the file was last accessed.
  • File Permissions:
    • Read Permission: Indicates whether the file can be read.
    • Write Permission: Indicates whether the file can be modified or overwritten.
    • Execute Permission: Indicates whether the file can be executed as a program.
  • Owner: The user or entity that owns the file.
  • Group: The group to which the file belongs.
  • File Path: The location of the file in the file system hierarchy.

File Creation and Manipulation

ActionDescription
Create FileGenerate a new file in the file system with a specified name and attributes.
Open FileAccess an existing file in the file system for reading, writing, or both.
Read from FileRetrieve data from an opened file for processing or display.
Write to FileStore data into an opened file, either appending to the existing content or overwriting it.
Close FileRelease the resources associated with an opened file, ensuring that any changes are saved and the file is properly closed.
Rename FileChange the name of an existing file in the file system while preserving its content and attributes.
Move FileTransfer a file from one location to another within the file system, potentially across different directories or drives.
Delete FileRemove a file from the file system, permanently erasing its content and attributes.
Copy FileDuplicate an existing file, creating a new file with identical content and attributes.
Change File PermissionsModify the access permissions of a file to control who can read, write, or execute it.
Set File AttributesAdjust the metadata associated with a file, such as its creation date, modification date, owner, group, and other attributes.
Check File ExistenceVerify whether a file exists in the file system, allowing for conditional operations based on its presence or absence.

File Organization and Search

ActionDescription
Create DirectoryGenerate a new directory (folder) in the file system with a specified name and attributes.
List Directory ContentsRetrieve a list of files and subdirectories contained within a specified directory, facilitating navigation and exploration.
Change DirectorySwitch the current working directory to a specified location within the file system, enabling navigation and access to files.
Remove DirectoryDelete a directory from the file system, along with all its contents, recursively erasing files and subdirectories within it.
Copy DirectoryDuplicate an existing directory, creating a new directory with identical content and attributes.
Move DirectoryTransfer a directory from one location to another within the file system, potentially across different directories or drives.
Rename DirectoryChange the name of an existing directory in the file system while preserving its contents and attributes.
Search for FilesConduct a search operation within the file system to locate files matching specified criteria, such as name, size, type, or content.
Recursive SearchPerform a recursive search operation, traversing through directories and subdirectories to locate files matching the search criteria.
File IndexingCreate and maintain an index of files within the file system, enabling faster and more efficient search operations by organizing files based on metadata.
Advanced Search FiltersApply advanced search filters to refine search results, allowing for complex queries based on multiple criteria and attributes.
File TaggingAssign tags or labels to files to categorize and organize them, facilitating easier retrieval and management through tag-based searching.

File Security and Metadata

ActionDescription
File PermissionsSet permissions to control who can read, write, or execute a file, specifying access rights for the owner, group, and others.
OwnershipAssign ownership of a file to a specific user or group, determining who has control over its access and management.
Access Control Lists (ACL)Define granular access control lists to specify detailed permissions for individual users or groups, allowing for fine-grained security management.
EncryptionApply encryption techniques to secure the contents of a file, preventing unauthorized access or tampering by encrypting data with cryptographic algorithms.
File IntegrityEnsure the integrity of a file by implementing measures such as checksums or digital signatures to detect any unauthorized modifications or corruption.
Audit TrailsMaintain audit trails to record and track actions performed on a file, including access attempts, modifications, and other security-related events.
MetadataStore metadata associated with a file, including attributes such as creation date, modification date, file type, size, owner, and other descriptive information.
Extended AttributesAttach extended attributes to a file to store additional metadata beyond the standard file attributes, enabling custom tagging or classification of files.
VersioningImplement versioning mechanisms to track and manage multiple versions of a file, enabling rollback to previous versions and maintaining revision history.
Secure DeletionSecurely delete files by overwriting their contents or using cryptographic techniques to ensure that the data cannot be recovered by unauthorized parties.
File Access LogsMaintain logs of file access activities to monitor and analyze file usage, providing insights into who accessed the file, when, and for what purpose.
Secure File TransferUtilize secure protocols and encryption methods for transferring files over networks, safeguarding data during transmission against eavesdropping or interception.

File Compression and Encryption

ActionDescription
CompressionReduce the size of a file by applying compression algorithms, such as ZIP, GZIP, or RAR, to eliminate redundancy and optimize storage space usage.
DecompressionExpand a compressed file back to its original size and format by decompressing it using compatible decompression algorithms.
EncryptionApply encryption techniques to secure the contents of a file, ensuring confidentiality and preventing unauthorized access by encrypting data with cryptographic algorithms.
DecryptionDecrypt an encrypted file to recover its original contents by applying compatible decryption algorithms and using the correct decryption key or passphrase.
Password ProtectionProtect files with passwords or passphrases to restrict access and prevent unauthorized viewing or modification, requiring the correct password for decryption.
Public Key EncryptionUtilize asymmetric encryption methods, such as RSA or ECC, to encrypt files using a public key and decrypt them using the corresponding private key for secure communication.
Symmetric EncryptionEmploy symmetric encryption algorithms, such as AES or DES, to encrypt and decrypt files using the same secret key, providing fast and efficient encryption for large files.
File IntegrityVerify the integrity of a file by applying cryptographic hash functions or digital signatures to detect any unauthorized modifications or corruption.
Secure File TransferTransfer encrypted files securely over networks using secure protocols, such as SFTP or HTTPS, to safeguard data during transmission against eavesdropping or interception.
Compression FormatsSupport various compression formats, including ZIP, GZIP, TAR, 7z, and RAR, providing flexibility in choosing the most suitable compression method for specific requirements.
Encryption AlgorithmsOffer a range of encryption algorithms with different levels of security and performance, allowing users to select the appropriate algorithm based on their security needs.
Compression EfficiencyEvaluate the compression efficiency of different algorithms and formats based on factors such as compression ratio, speed, and compatibility with existing tools and systems.

You can also read about the Multilevel Queue Scheduling, Multiprogramming vs Multitasking

Frequently Asked Questions

What is a system call?

System calls are special functions that manage OS routines in kernel mode. 
Kernel mode, also known as system mode, is a central processing unit (CPU) operating mode. While processes run in kernel mode, they have unrestricted access to the hardware.

What is a file?

A named collection of related data (or maybe typically the same data)  recorded (or stored) on secondary storage such as optical disks, magnetic disks, etc., is known as a file.
We can also say that a file is a sequence of bits, bytes, or lines whose meaning is defined by the file's creator.

What are the file operations?

The various operations can be performed on a file like reading, writing, opening, closing, etc. These operations are called file operations. The user performs file operations with the help of commands provided by the operating system.

Conclusion

In this blog, we learned about files and file operations. We studied different types of operations on the file: Create operation, open operation, write operation, read operation, reposition operation, delete operation, truncate operation, close operation, append operation, rename operation.

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