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📝 VI Editor (Powerful but Confusing at First)

What is vi?

vi is a terminal-based text editor in Linux/Unix systems.

• Old
• Extremely powerful
• Available on almost every Linux server
• Default editor on many servers (EC2, production machines)

📌 Important:

Even if Nano is easier, you MUST know vi Because sometimes Nano is not installed, but vi always is.

Why vi feels difficult for beginners 😵

Because vi has MODES.

Nano → type directly Vi → depends on which mode you are in

👉 This is the most important concept.

🔁 VI MODES (MOST IMPORTANT PART)

vi works in three main modes:

When you open vi, you are NOT in typing mode.

You start in Normal mode ❗

1️⃣ Normal Mode (Default mode)

This is the command mode for movement and actions.

• You cannot type text
• Every key is treated as a command

Examples:

• dd → delete line
• yy → copy line
• p → paste
• gg → go to top

📌 If something weird happens → You are probably in Normal mode 😄

2️⃣ Insert Mode (Typing mode)

This is where you can type text normally.

To enter Insert mode, press:

When Insert mode is active:

• Bottom shows: -- INSERT --

To exit Insert mode:

ESC

👉 ESC is your best friend in vi.

3️⃣ Command Mode (Colon : mode)

Used for:

• Save
• Quit
• Search
• Replace
• Line numbers

You enter command mode by typing:

:

(while in Normal mode)

Example:

:w
:q
:wq

🚀 Opening a file in vi

vi file.txt

If file doesn’t exist:

• It will be created when you save

✍️ BASIC WORKFLOW (VERY IMPORTANT)

This is how 90% of people use vi:

1. Open file
2. Press i
3. Type text
4. Press ESC
5. Save and quit

Let’s see commands.

💾 Save and Exit Commands (MUST KNOW)

📌 Examples:

Save only:

:w

Save and exit:

:wq

Exit without saving:

:q!

🧭 MOVEMENT (Navigation) – Core vi skill

You can use arrow keys, BUT real vi users use:

Why?

• Faster
• Hands stay on keyboard

Line & file movement

✂️ DELETE, COPY, PASTE (VERY IMPORTANT)

Delete

📌 Delete = cut (stored in buffer)

Copy (Yank)

Paste

🔁 Undo and Redo

📌 Undo is life saver.

🔍 SEARCHING (Very useful)

Search forward

/word

Search backward

?word

Press:

• n → next match
• N → previous match

🔄 SEARCH & REPLACE (POWER FEATURE)

Format:

:s/old/new/

Examples:

Replace first match in line:

:s/java/spring/

Replace all in line:

:s/java/spring/g

Replace in entire file:

:%s/java/spring/g

Replace with confirmation:

:%s/java/spring/gc

🔢 Line Numbers (VERY IMPORTANT IN DEBUGGING)

Show line numbers:

:set number

Hide line numbers:

:set nonumber

Shortcut:

:set nu

📌 VISUAL MODE (Text selection)

Enter Visual mode:

v

• Move cursor to select text

Commands after selection:

• d → delete
• y → copy

Visual line mode:

V

⚙️ REAL PRODUCTION USAGE EXAMPLES

Edit config file on EC2

vi /etc/nginx/nginx.conf

Edit environment variables

vi ~/.bashrc

Edit application properties

vi application.properties

⚠️ COMMON BEGINNER MISTAKES

❌ Typing without entering Insert mode ❌ Forgetting to press ESC ❌ Not knowing how to quit ❌ Panic when screen freezes

✅ Solution:

ESC
:q!

Always works 😄

🧠 MENTAL MODEL (IMPORTANT)

Think like this:

• Normal mode → THINK
• Insert mode → TYPE
• Command mode → CONTROL

🆚 VI vs NANO (Quick Comparison)

🧾 MUST-MEMORIZE COMMANDS (Cheat Sheet)

i        → insert
ESC      → normal mode
:w       → save
:q       → quit
:wq      → save & quit
:q!      → quit force
dd       → delete line
yy       → copy line
p        → paste
u        → undo
/word    → search
:set nu  → line numbers

Final Advice ❤️

Don’t try to memorize everything at once.

Start with:

1. i
2. ESC
3. :wq
4. dd
5. /search

That’s enough for real-world server work.