Vim

Vim (Vi Improved) is a powerful text editor with different modes for editing and commands.

Command	Description
vim file.txt	Open or create a file
i	Enter insert (edit) mode
Esc	Exit insert mode
:w	Save changes
:q	Quit
:wq	Save and quit
:q!	Quit without saving
/word	Search for a word
n	Go to next search match
:%s/old/new/g	Replace all “old” with “new”

Example:

vim notes.txt

Type i to start editing.
When finished, press Esc, then type :wq to save and exit.