File Management System Basics

Study Notes

File Pointer: Functions like a bookmark to track where the operating system reads or writes in a file.
File Open Count: Similar to library borrowings, this tracks how many programs currently have a file open to prevent data corruption from simultaneous modifications.
Disk Location: Identifies the physical location on the hard drive for a file through an internal directory akin to a library catalog.
Access Rights (Permissions): Defines who can access a file and what actions they can perform, including read, write, execute, and delete.

File Name: Identifies and references files within the system (e.g., myfile.txt).
File ID: Unique identifier for the operating system to track files internally, functioning like a serial number.
Type: Describes the file's format, indicating the appropriate program to open it (e.g., Text Document).
Location: Specifies the file's place in the system, aiding in organization and search (e.g., C:\Users\YourUsername\Documents).
Size: Indicates the storage space occupied by a file, measured in bytes (e.g., 1.2 KB).

Read: Permissions allow users to view the file's contents (User, Group, Everyone).
Write: Only the file owner and group members can modify the file.
Execute: Indicates that the file is not executable.

Creating a File: Involves finding space on a hard drive and cataloging the new entry in the directory.
Writing to a File: A system call is used; it includes a file identifier and write pointer to track where data is being added.
Reading a File: Also uses a system call where a read pointer determines the current reading position.
Repositioning in a File: Allows moving within the file using pointers for both reading and writing.
Deleting a File: Marks the space as free and removes the entry from the directory.
Truncating a File: Deletes data after a certain point but retains the directory entry for the file.

File Extension: Indicates the file type (e.g., .txt, .pdf, .jpg), assisting the operating system in opening it correctly.
Magic Numbers: Special byte patterns at the beginning of files that help identify the file type even if the extension is incorrect, enhancing data protection.

Organization: Categorizations help group files by type for easier management.
Correct File Opening: Ensures the right program is used for file interaction based on extension or magic number.
Data Protection: Helps prevent the misuse of files by verifying their actual content type.