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Linux — The vi Editor

Short & clear revision notes · 9 topics

01 · What is vi?

vi is the standard text editor built into every Unix/Linux system. An improved version called VIM (Vi IMproved) is also widely available.

Why vi is the de facto standard:

  • Available on all flavours of Unix/Linux
  • Consistent behaviour across systems
  • Very lightweight — requires few resources
  • More user-friendly than older editors like ed or ex

Opening vi

Command What it does
vi filename Open a file (creates it if it doesn't exist)
vi -R filename Open in read-only mode
view filename Open in read-only mode (same as -R)

💡 When vi opens, you see ~ on empty lines — this means those lines don't exist in the file yet. A blank-looking line without ~ contains invisible characters (space, tab, newline).

02 · The Two Modes — Most Important Concept

vi always has exactly one active mode. Getting this wrong is the #1 cause of confusion.

┌─────────────────────────────────────────────────────┐
│                   COMMAND MODE                      │
│   (default on open — navigate, delete, copy, save)  │
│                                                     │
│        press i / a / o  →  INSERT MODE              │
│        ←  press Esc  ←                              │
│                                                     │
│                   INSERT MODE                       │
│           (type text into the file)                 │
└─────────────────────────────────────────────────────┘
Mode What you can do How to enter
Command mode Navigate, delete, copy, save, quit Press Esc (or Esc twice to be safe)
Insert mode Type text into the file Press i, a, o, etc.

⚠️ vi is case-sensitive. i and I do different things. Always check your mode before typing commands.

03 · Saving & Quitting

All save/quit commands are typed in command mode.

Command What it does
:w Save the file (write)
:q Quit (only works if no unsaved changes)
:wq Save and quit
ZZ Save and quit (fastest way)
:q! Quit without saving — discard all changes
:w filename2 Save as a different filename

💡 If you're unsure what mode you're in, press Esc twice — you'll always land in command mode.

04 · Moving Around — Navigation Commands

Must be in command mode. You can prefix most commands with a number — e.g. 5j moves down 5 lines.

Basic cursor movement

Command Movement
h Left one character
l Right one character
k Up one line
j Down one line

Word & line movement

Command Movement
w Forward to next word
b Backward to previous word
0 or | Beginning of current line
$ End of current line
( Beginning of current sentence
) Beginning of next sentence
{ One paragraph back
} One paragraph forward

File-level movement

Command Movement
1G First line of file
G Last line of file
nG Go to line n
:n Go to line n
H Top of screen
M Middle of screen
L Bottom of screen

Scroll commands (Ctrl key)

Command Movement
Ctrl+f Scroll forward one full screen
Ctrl+b Scroll backward one full screen
Ctrl+d Scroll forward half screen
Ctrl+u Scroll backward half screen
Ctrl+e Scroll screen up one line
Ctrl+y Scroll screen down one line
Ctrl+l Redraw the screen

05 · Inserting Text — Enter Insert Mode

From command mode, use any of these to enter insert mode at different positions:

Command Where text is inserted
i Before the cursor
I At the beginning of the current line
a After the cursor
A At the end of the current line
o New line below the cursor
O New line above the cursor

💡 Press Esc to return to command mode after typing.

06 · Deleting, Changing & Copying

Deleting (command mode)

Command What it deletes
x Character under cursor
X Character before cursor
dw From cursor to end of word
d^ From cursor to beginning of line
d$ or D From cursor to end of line
dd Entire current line
2dd Two lines (prefix any command with a number)

Changing

Command What it does
r Replace one character (stays in command mode)
R Overwrite characters until Esc
cw Change word from cursor to end
cc Clear entire line, enter insert mode
s Replace current character, enter insert mode
S Delete line, enter insert mode

Copy & Paste (Yank)

Command What it does
yy Copy (yank) current line
yw Copy current word
p Paste after cursor
P Paste before cursor

07 · Searching

String search (whole file)

Command What it does
/word Search forward (downward) for word
?word Search backward (upward) for word
n Repeat search in same direction
N Repeat search in opposite direction

Character search (current line only)

Command What it does
fc Move forward to character c on current line
Fc Move backward to character c on current line
tc Move forward to just before character c
Tc Move backward to just after character c

Regex special characters in search

Character Meaning
^ Start of line
$ End of line
. Any single character
* Zero or more of previous character
[ Start of a matching set

Find & Replace

:s/search/replace/g     # replace all occurrences on current line
:%s/search/replace/g    # replace all occurrences in entire file

08 · Advanced & Useful Commands

Command What it does
u Undo last change
U Restore current line to original state
J Join current line with the next
~ Toggle case of character under cursor
<< Shift current line left
>> Shift current line right
Ctrl+G Show filename, current position, and total lines
:f Show filename and current position as %
:! command Run a shell command without leaving vi

Working with multiple files

Command What it does
:e filename Open another file
:e # Toggle between two open files
:n Go to next file (when multiple files open)
:p Go to previous file
:r file Read a file and insert it after current line
:cd dirname Change working directory

09 · :set — Customise vi Behaviour

Type :set followed by the option in command mode:

Command What it does
:set nu Show line numbers
:set ic Ignore case when searching
:set ai Auto-indent new lines
:set noai Turn off auto-indent
:set sw=4 Set shift width to 4 spaces
:set wm=2 Auto word-wrap at 2 characters from margin
:set ws Wrap search — continue from top when reaching bottom
:set ro Set file to read-only
:set term Print terminal type

Quick Reference Cheatsheet

MODES:
  Esc           → command mode (always safe to press twice)
  i             → insert before cursor
  a             → insert after cursor
  o             → new line below

SAVE & QUIT:
  :w            → save
  :q            → quit
  :wq or ZZ     → save and quit
  :q!           → quit without saving

NAVIGATE:
  h j k l       → left down up right
  w / b         → next / previous word
  0 / $         → start / end of line
  G / 1G        → last / first line
  :n            → go to line n

DELETE:
  x             → delete character
  dd            → delete line
  dw            → delete word
  D             → delete to end of line

COPY & PASTE:
  yy            → copy line
  p / P         → paste after / before

SEARCH:
  /word         → search forward
  ?word         → search backward
  n / N         → next / previous match
  :s/old/new/g  → replace on current line
  :%s/old/new/g → replace in entire file

UNDO:
  u             → undo last change
  U             → restore current line

Linux vi Editor Notes — for revision use