Linux-command-cheat-sheet2

Mastering Linux Commands with Examples

This repository provides a comprehensive guide to using Linux commands, with examples and screenshots for clarity.

Table of Contents

1. User and Terminal Details
2. File Operations
   • Creating, Viewing, and Appending
3. Word Count and Line Count
4. Head and Tail Commands
5. Linux Command-Line Shortcuts
6. Linux File System Hierarchy
7. Move Command
8. Copy Command
9. TTY and Virtual Terminals
10. Getting Command Information
11. Editing with Vim

---

1. User and Terminal Details

To display the current user and terminal details:

2. File Operations

Create a file and append to it:

• cat > f1
  • Purpose: Creates or overwrites the file f1.
  • Behavior: If f1 exists, its content will be erased, and new input will replace it. If f1 does not exist, it creates a new file.
  • Use Case: Start fresh with a new file or replace existing content.

• cat >> f1
  • Purpose: Appends new content to the end of the file f1.
  • Behavior: If f1 exists, new input will be added to the end of the file without erasing the previous content. If f1 does not exist, it creates a new file.
  • Use Case: Add more content to an existing file without deleting its current data.

View file content:

• cat f1
• less f1
• gedit f1 # like notepad
• evince f1 # Open PDF file

3. Word Count (wc) Command

Display line, word, and character count of a file:

6: Number of lines

7: Number of words

33: Number of characters

Commands for specific counts:

• Lines: wc -l f1
• Words: wc -w f1
• Characters: wc -c f1

4. Head and Tail Commands

Display first/last lines of a file:

• head

• tail

5. Linux Command-Line Shortcuts

Key shortcuts for efficient command-line use:

• Ctrl + A: Move to the beginning of the line
• Ctrl + E: Move to the end of the line
• Ctrl + R: Search through command history
• Ctrl + U: Clear the current line
• Ctrl + L: Clear the screen

6. Linux File System Hierarchy

The Linux File System Hierarchy is an organized structure of directories and files that follows a standard layout, making it easy to navigate and manage. Here’s an overview of the main directories:

• Root Directory: / The base of the Linux file system. All other directories and files stem from this root directory.

• Key Directories in Linux

• Paths: Absolute & Relative

  • Absolute path:Starts from the root (/) directory.

    cd /var

  • Relative path:Starts from the current working directory.

    cd /root/Desktop

7. Move Command

Move or rename files and directories:

• Rename

• Move

8. Copy Command

• Copy a folder with its contents:

• Copy file content to another file:

9. TTY and Virtual Terminals

• Display terminal number:
  • tty
    • TTY stands for Teletypewriter, a term inherited from the early days of computing when physical terminals were used.
    • In modern Linux, a TTY represents a virtual terminal or text console that allows users to interact with the system.
    • Each TTY has a unique terminal number.

• Switch to a virtual terminal:
  • Virtual terminals are text-based user interfaces that run independently of the graphical desktop environment.
  • By default, Linux provides 6 virtual terminals

10. Getting Command Information

• date --help
• man ls
• pinfo mkdir
  • Navigation:
    • n: Next
    • p: Previous
    • d: Index

11. Editing with Vim

Basic Commands:

• Insert mode: Press i
• Save and exit: :wq!
• Set line numbers: :se nu
• Remove line numbers: :se nonu

Advanced Editing:

• Copy three line: 3yy, Paste: p
• Undo: u, Redo: Ctrl + r
• Delete 10 lines: 10d
• Copy 2 words: 2ya, Paste: p