Linux File System

LINUX FILESYSTEM HIERARCHY

Chapter 6 - RH124 Hands-On Focus

FILESYSTEM TREE OVERVIEW

  • Single inverted tree structure: The entire filesystem is organized as a single tree with / (the root directory) at its top.
  • Directories branch downward from /: All other directories and files create subdirectories under the root directory.
  • All paths:
    • Absolute paths: Start from the root directory /.
    • Relative paths: Based on the current directory the user is in.

IMPORTANT DIRECTORIES

  • /boot: Contains bootloader files essential for the system startup.
  • /dev: Contains device files which represent hardware devices.
  • /etc: Holds system configuration files for the operating system and installed applications.
  • /home: Directory containing user data, structured per user (e.g., /home/username).
  • /root: The home directory for the root user (the superuser or admin).
  • /run: Contains runtime process data that is maintained during system uptime.
  • /tmp: Temporary files are stored here, often cleared at boot.
  • /usr: Contains user programs and libraries, typically for user applications.

PATH TYPES

  • Absolute Path: Always starts with /, representing the complete path from the root.
  • Relative Path: Depends on the current working directory.
  • Case Sensitivity: Paths in Linux are case-sensitive, so /Home and /home refer to different directories.
  • Filename Spaces: To avoid issues, it is advised to refrain from using spaces within filenames.

USEFUL COMMANDS

  • pwd: Print working directory, displays the current path.
  • ls: List files in the current directory. Can be used with options:
    • -l: Long listing format, shows detailed file information.
    • -a: Includes hidden files (those starting with a dot).
    • -R: Lists files in the directory and all subdirectories recursively.
  • cd: Change directory, used to navigate between directories.
  • touch: Create or update the timestamp of a file.

HANDS-ON PRACTICE: EXPLORING DIRECTORIES

  • Try Commands:
    • pwd: To see the current directory.
    • ls on /etc to list files in system configurations.
    • ls -1 /var/log: List files in /var/log in a single column.
    • ls -a ~: List all files, including hidden ones in the home directory.

HANDS-ON: NAVIGATING

  • Try Commands:
    • cd /var/log: Change to the /var/log directory.
    • cd ..: Move up one directory level to the parent directory.
    • cd -: Switch back to the previous directory you were in.
    • cd ~/Documents: Navigate to the Documents directory under your home.

HANDS-ON: CREATING FILES

  • Try Commands:
    • touch ~/Documents/test1.txt: Create a file named test1.txt in Documents.
    • touch ~/Videos/movie1.ogg: Create a file named movie1.ogg in Videos directory.
  • Verify Created Files: Use ls on Documents and Videos to check the existence of the files.

HIDDEN FILES & SPECIAL DIRS

  • .: Represents the current directory.
  • ..: Represents the parent directory.
  • Files starting with . are considered hidden and do not show up in regular listings unless specified.
  • Try Command: Use ls -la ~ to display all files, including hidden ones in the home directory.

PRACTICE CHALLENGE

  1. Navigate to /etc and list all files within that directory using ls.
  2. Create 2 practice files in ~/tmp_test directory.
  3. Move up two directories using relative paths (e.g. cd .. twice).
  4. Return to the original directory using cd - multiple times.