inode

What is an inode?

An inode (index node) is a data structure used in UNIX-like systems to store information about files and directories.

Key Points

  • Data Structure: An inode stores attributes of files and directories.
  • Attributes: Includes information like file ownership, modification date, file size, and access permissions.
  • UNIX Systems: Primarily used in UNIX-like operating systems.

Detailed Explanation

  1. Basic Concept: An inode contains metadata about a file or directory. It does not store the actual data of the file, but rather information about it.
  2. Components Stored in an Inode:
    • File Owner: Who owns the file.
    • Modification Date: When the file was last updated.
    • File Size: How large the file is.
    • Access Rights: Permissions related to who can read or write the file.
    • Data Location: Information on where the actual file data is stored on the disk.
  3. Example: If a file named example.txt is created in a directory, its content and its inode are stored separately:
    • The actual content of example.txt is saved in a data block.
    • The inode stores the attributes of example.txt and points to where the file content is located.
  4. File Access Flow:
    • To access example.txt, the system looks up the directory to find the inode number associated with example.txt.
    • The inode is then used to retrieve the file’s attributes and the location of the file’s data.
  5. Identification: Each inode is assigned a unique number, known as the inode number, which helps in identifying it.

Summary: An inode is a data structure that holds metadata about files and directories in UNIX-like systems. It includes information such as file attributes and the location of the file data.