--description--

Terminal, Shell, and Command Line Basics

• Command line: A text interface where users type commands.
• Terminal: The application that provides access to the command line.
• Terminal emulator: Adds extra features to a terminal.
• Shell: Interprets the commands entered into the terminal (e.g., Bash).
• PowerShell / Command Prompt / Microsoft Terminal: Options for accessing the command line on Windows.
• Terminal (macOS): Built-in option on macOS, with third-party alternatives like iTerm or Ghostty.
• Terminal (Linux): Options vary by distribution, with many third-party emulators like kitty.
• Terminology: Though "terminal," "shell," and "command line" are often used interchangeably, they have specific meanings.

Command Line Shortcuts

• Up/Down arrows: Cycle through previous/next commands in history.
• Tab: Autocomplete commands.
• Control+L (Linux/macOS) or typing cls (Windows): Clear the terminal screen.
• Control+C: Interrupt a running command (also used for copying in PowerShell if text is selected).
• Control+Z (Linux/macOS only): Suspend a task to the background; use fg to resume it.
• !!: Instantly rerun the last executed command.

Bash Basics

• Bash (Bourne Again Shell): Widely used Unix-like shell.
  Key commands:

  • pwd: Show the current directory.
  • cd: Change directories.
    • .. refers to the parent directory (one level up).
    • . refers to the current directory.
  • ls: List files and folders.
    • -a: Show all files, including hidden files.
    • -l: Show detailed information about files.
  • less: View file contents one page at a time with navigation options, including scrolling backward and searching.
  • more: Display file contents one screen at a time, with limited backward scrolling and basic navigation.
  • cat: Show the entire file content at once without scrolling or navigation, useful for smaller files.
  • mkdir: Create a new directory.
  • rmdir: Remove an empty directory.
  • touch: Create a new file.
  • mv: Move or rename files.
    • Rename: mv oldname.txt newname.txt
    • Move: mv filename.txt /path/to/target/
  • cp: Copy files.
    • -r: Recursively copy directories and their contents.
  • rm: Delete files.
    • -r: Recursively delete directories and their contents.
  • echo: Display a line of text or a variable's value.
    • Use > to overwrite the existing content in a file. (e.g., echo "text" > file.txt)
    • Use >> to append output to a file without overwriting existing content (e.g., echo "text" >> file.txt).
  • exit: Exit the terminal session.
  • clear: Clear the terminal screen.
  • find: Search for files and directories.
    • -name: Search for files by name pattern (e.g., find . -name "*.txt").
  • Use man followed by a command (e.g., man ls) to access detailed manual/help pages.

Command Options and Flags

• Options or flags: modify a command's behavior and are usually prefixed with hyphens:
  • Long form (two hyphens):
    • Example: --help, --version
    • Values are attached using an equals sign, e.g., --width=50.
  • Short form (one hyphen):
    • Example: -a, -l
    • Values are passed with a space, e.g., -w 50.
    • Multiple short options can be chained together, e.g., ls -alh.
• --help: You can always use a command with this flag to understand the available options for any command.

--assignment--

Review the Bash Commands topics and concepts.