vi is a terminal text editor available on virtually every Unix system. When you open a file, vi copies it into a buffer, lets you edit it, and writes it back on save. Vim (Vi IMproved) extends vi with syntax highlighting, plugins, GUI support, and much more.

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The two modes

Vi operates in two modes:

• Command mode — every keystroke is a command. This is where you start when you open a file.
• Insert mode — keystrokes produce text, like a normal editor.

Switch to insert mode with i, I, a, A, or similar commands. Return to command mode with ESC.

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Opening files

vi filename          # open an existing or new file
vi -p file1 file2   # open files in separate tabs
vi -o file1 file2   # open files in horizontal splits
vi -O file1 file2   # open files in vertical splits

When a file opens, tildes (~) on the left indicate empty lines. The status line at the bottom shows the filename and file info.

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Saving and quitting

Command	Action
ZZ	Save and quit
:wq or :x	Save and quit (ex command)
:q!	Quit without saving
:w	Save without quitting

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Basic editing

Inserting text

Command	Action
i	Insert before cursor
I	Insert at beginning of line
a	Append after cursor
A	Append at end of line

Changing text

Command	Action
r	Replace one character (stays in command mode)
~	Toggle case of character under cursor
cw	Change word
cc / C	Change line / rest of line
s	Substitute character at cursor
S	Substitute entire line

Deleting text

Command	Action
dw	Delete word
dd	Delete line
dl or x	Delete one character
D	Delete to end of line

Repeat and undo

Command	Action
.	Repeat the last command
u	Undo last change
U	Undo all changes on current line
J	Join current line with the line below

Tip: Most commands accept a count prefix. 2dd deletes two lines, 5dw deletes five words, and 20i hi, there! ESC inserts the phrase 20 times.

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Movement

Basic cursor movement

Command	Action
h j k l	Left, down, up, right
e / b	Forward / backward one word
+ / -	First character of next / previous line

Line navigation

Command	Action
0 or ^	Beginning of line
$	End of line

File navigation

Command	Action
#G	Go to line number #
G	Go to last line
``	Return to previous position
H / M / L	Top / middle / last line on screen

Scrolling

Command	Action
^F / ^B	Scroll forward / backward one full screen
^D / ^U	Scroll down / up half a screen

Tip: Show line numbers with :set nu or :set number. Hide them with :set nonu.

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Searching

Pattern search

Command	Action
/pattern	Search forward for pattern
?pattern	Search backward for pattern
n / N	Repeat search forward / backward

Search patterns support regular expressions — ., *, [], and more.

Character search (within a line)

Command	Action
fx	Find character x forward on current line
Fx	Find character x backward on current line
; / ,	Repeat character search forward / backward

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Cutting, copying, and pasting

Deleted text is saved to a buffer automatically and can be pasted with p.

Yank (copy) and put (paste)

Command	Action
yy or Y	Yank (copy) current line
yw	Yank word
y$	Yank to end of line
p	Paste after cursor
P	Paste before cursor

Unnamed buffers

Vi saves your last nine deletions in numbered buffers. Paste the second-to-last deletion with "2p.

Named buffers (a–z)

Use named buffers to save specific yanks or deletions:

Command	Action
"zdw	Delete into buffer z
"zyy	Yank into buffer z
"zp	Paste from buffer z

Using a capital letter (e.g. "Zyy) appends to the named buffer rather than replacing it.

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Ex commands

Every time you type : in vi, you invoke the ex line editor — vi’s underlying engine. Ex commands are powerful because they can operate on ranges of lines at once.

Line addressing

Address	Meaning
3	Line 3
.	Current line
$	Last line
%	Every line in the file
/pattern/	Next line matching pattern

Examples:

• :3,18d — delete lines 3 through 18
• :.,$ d — delete from current line to end of file
• :%d — delete all lines
• :/pattern/d — delete the next line matching pattern

Global search and replace

:s/old/new/          # replace first match on current line
:s/old/new/g         # replace all matches on current line
:%s/old/new/g        # replace all matches in the whole file
:%s/old/new/gc       # replace all matches, with confirmation

Combine with the global command to restrict replacements to matching lines:

:g/pattern/s/old/new/g

Working with multiple files

:e filename          # edit another file (save current first with :w)
:n                   # move to next file in the argument list
:r filename          # read another file's contents into current file
:args                # list all files currently being edited

Search and replace across multiple buffers

:bufdo %s/pattern/replace/ge | update   " replace in all open buffers
:argdo %s/pattern/replace/ge | update   " replace in all argument files

The e flag suppresses errors when a pattern isn’t found. update only writes files that were changed.

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Vim (Vi IMproved)

Vim adds a substantial layer of features on top of vi:

Syntax and indentation

:syntax on        " enable syntax highlighting
:set autoindent   " enable automatic indentation
:set number       " show line numbers

Session persistence

Vim stores session history in ~/.viminfo, allowing it to remember your position, yank history, and command history between sessions — even across different files.

Transparent editing

Vim can open compressed or archived files directly (e.g. myfile.tar.gz) and lets you browse and edit directory listings using standard navigation commands.

Meta-information registers

Vim exposes several read-only registers for inserting metadata:

Register	Contents
%	Current filename
#	Alternate filename
:	Last ex command executed
.	Last inserted text

Plugins and configuration

Vim supports a rich ecosystem of plugins, configurable through ~/.vimrc. Options worth setting early:

:set hidden          " allow unsaved buffers in the background
:set autowriteall    " auto-save when switching buffers

Popular plugin managers include vim-plug and Pathogen. Plugins can add IDE-like features including file trees, fuzzy finding, git integration, and language server support.