Vim

What is Vim?

Vim is a greatly improved version of the good old UNIX editor Vi. Many new features have been added: multi-level undo, syntax highlighting, command line history, on-line help, spell checking, filename completion, block operations, script language, etc. There is also a Graphical User Interface (GUI) available. Still, Vi compatibility is maintained, those who have Vi "in the fingers" will feel at home. See runtime/doc/vi_diff.txt for differences with Vi.
This editor is very useful for editing programs and other plain text files. All commands are given with normal keyboard characters, so those who can type with ten fingers can work very fast. Additionally, function keys can be mapped to commands by the user, and the mouse can be used.
Vim runs under MS-Windows (XP, Vista, 7, 8, 10), macOS, Haiku, VMS and almost all flavours of UNIX. Porting to other systems should not be very difficult. Older versions of Vim run on MS-DOS, MS-Windows 95/98/Me/NT/2000, Amiga DOS, Atari MiNT, BeOS, RISC OS and OS/2. These are no longer maintained.
——Github/Vim

How to use Vim?

In Terminal

vim : Open Vim
vim [filename] : Open [filename] in Vim

Modes

In Vim, there are three modes of operation: Normal, Insert, and Visual.

Normal mode

Normal mode is the initial mode of the Vim editor. When you open a new file edit an existing one, it starts in normal mode by default. In normal mode, you cannot insert any character. Normal mode is also known as command mode because all the keystrokes you perform are interpreted as commands.

To access normal mode from other modes, press Esc key.

Insert mode

Insert mode is where you can insert your text in the file. This mode inserts every character you type at the current cursor location.

Visual mode

Visual mode allows you to select text so that you may perform certain operations (cut, copy, delete) on it.

Changing the modes

When creating or opening a file in vim, it first opens in Normal mode.
Switch to Insert mode from Normal mode: i or I, o, O, a, A.
Switch to Visual mode from Normal mode: v or V
Switch between Inset mode and Visual mode: shift to Normal mode first.

Commands (in Normal mode)

Key	Command
`:w`	Write the file to the disk
`:w [filename]`	Save the file as [filename]
`:q`	Quit vi without saving the file
`:wq`	Write the file to disk and quit vim
`:wq [filename]`	Quit and save the file as [filename]
`:q!`	Ignore the warning and discard the change

Moving the cursor

Key	Command
`h` / `Left`	Move the cursor left one character
`j` / `Down`	Move the cursor down one line
`k` / `Up`	Move the cursor up one line
`l` / `Right`	Move the cursor right one character
`w`	Move the cursor forward one word
`b`	Move the cursor backward one word
`Control` `f` / `Page Down`	Move the cursor forward one page
`Control` `b` / `Page Up`	Move the cursor backward one page
`[number]gg`	Move the cursor to line [number]
`[number]j`	Move the cursor down [number] lines
`[number]k`	Move the cursor up [number] lines

Finding text

Key	Command
`/[text]`	Find all [text]
`n`	Move to next [text]
`Shift` `n`	Move to previous [text]

Inserting text

Key	Command
`I`	Insert text at the beginning of the line
`i`	Insert text before the current cursor location
`a`	Insert text after the current cursor location
`o`	Create a new line for the text below the current cursor location
`O`	Create a new line for text above the current cursor location

Changing text

Key	Command
`cc`	Remove the whole line and start Insert mode
`c[number]c`	Remove the whole [number] lines and start Insert mode
`s`	Remove the character under the cursor and start Insert mode
`r`	Replace the character under the cursor

Copying & Pasting

Key	Command
`y`	Copy the selected text to clipboard
`yy`	Copy current line
`P`	insert the text before the cursor
`p`	Insert the text at the point after the cursor

Deleting text

Key	Command
`X`	Delete the character before the current location
`x`	Delete the character under the current location
`D`	Cut to the end of line
`dd`	Cut current line

Undo & Redo

Key	Command
`u`	Undo last change
`Control` `r`	Redo last change

Customize Vim

Enter vim ~/.vimrc in Terminal

syntax on : Code highlighting
set number : Line number

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