Linux Chapter 3: Directories and Files

Chapter 3: Directories and Files in Linux

• Files: Used to store data. Various types exist, including text, images, audio files, scripts, databases, and more.
• Directories: Used for organizing files. Directory structures are organized in a hierarchical tree format.
• File System (FS): Defines how data is organized on a storage medium. In Linux, the FS uses a tree structure of directories and subdirectories, starting from the root directory "/".
• Linux Directory Hierarchy: Displays a tree structure showing the root directory (/) and its subdirectories, including /bin, /etc, /home, /opt, /tmp, /usr, and /var, along with user directories like user1 and user2 and their subfolders, and other directories.
• Introduction (continued): A graphical directory structure also shows how directories are organized, including the root (/), home, user, and other directories. Additional directories exist for various functions and system settings.
• Path: Represents the location of a file or directory.
• A combination of / (root directory) and alpha-numeric characters.
• Examples include /home/duck/myMusic/song.mp3 and /home/cat/myProject.
• / has two meanings:
  • a separator within a path
  • a directive to show the path begins from the root directory
• File and Directory Names:
  • Case sensitive -- this means file names and directory names must be entered with correct letter-case distinctions.
  • Forbidden Characters : '/' is a forbidden character, and spaces, enter, and special characters are not recommended.
  • Often include extensions (.txt,.pdf, .sh etc.). These extensions help determine the data type within the file.
• Absolute vs Relative Paths:
  • Absolute Path: Starts with a /, defining the complete path from the root directory. Example: /home/user/documents/file.txt
  • Relative Path: Doesn't begin with /, defining the path from the current working directory. Example: documents/file.txt or myFolder/data.
• . (dot): Represents the current directory or the directory itself. If you run a command in a directory, the command works on that directory.
• .. (dot-dot): Refers to the parent directory. Used for navigating up a level in the directory structure.
• Home Directory (Login Directory): The location /home/username, where data related to the user is stored. The user's current working directory in a new terminal defaults to their home directory. A tilde (~) represents the home directory.
• Directory Operations:
  • Print working directory: Shows the current directory or the path to the current directory. The command is: pwd
  • Change directory: Navigates to another directory in the file system. The command is: cd [path]
  • List directory contents: Displays the files and subdirectories contained in a directory. The command is: ls [options] [rep 1] [rep 2] ... [rep n]
  • Make directory: Creates a new directory. The command is: mkdir [options] rep 1 [rep 2] ... [rep n]
  • Remove directory: Deletes an empty directory. The command is rmdir [options] rep 1 [rep 2] ... [rep n]
  • Rename/Move directory: Changes a directory's name or moves it to a different location. Command: mv [options] [rep source] [rep destination]
  • Find directory location: locates a directory's location. Commands include: find, locate
  • Copy directory Contents: Copies contents of a directory. Command: cp -r [options] [rep source] [rep destination]
• File Operations:
  • Create file: Creates new files. The command is touch [options] file1 [file2] ...[filen]
  • Delete file: Deletes a file. The command is rm [options] [file1] [file2] ...[filen]
  • Read file content: Reads the content of a file. Commands are: cat, more, less
  • Rename File: Changes a file's name. Command: mv [options] [file source] [file or rep destination]
  • Find file location: Locates the location of a file. Commands include: find, locate
  • Copy file: Copies a file. Command: cp [options] [file source] [file destination]
  • Determine file type: Shows the file type. Command: file [options] nameFile
  • Search file for word: Searches a file for a given word. command: grep [options] word file
  • Search and Replace: Searches and replaces a word in a file. Command: sed [options] 'command' filename
• Shortcuts (Raccourcis): Keyboard shortcuts available within the shell for navigating through history or commands.
• Special Characters: Characters used to show specific actions. These characters are often included in file and directory names. (e.g. ~, *, ?)
• Hidden Files and Folders: Files and folders hidden from view in the operating system. The command ls -a displays hidden files.
• Archiving and Compression: Collecting multiple files and making them into one file for easy handling, storage, and transfer (e.g. for backups). The tar command is used, with options to create, view, extract, or add files in and out of an archive.
• Backup using relative/absolute Paths: When backing up files or folders, you can specify the path in relation to the current folder (relative path or an absolute path that starts from the root directory).

Explore the essential concepts of directories and files in Linux through this quiz. Learn about the hierarchical structure of directories, the different types of files, and the Linux file system organization. Test your knowledge on the layout and function of various directories within the Linux environment.