Unix

vi editor

i - Insert at cursor (goes into insert mode)

ESC - Terminate insert mode

u - Undo last change

C - Delete contents of a line after the cursor and insert new text. Press ESC key to end insertion.

D - Delete contents of line after the cursor

dd - Delete line

3dd - Delete 3 lines.

dw - Delete word

~ - Change case of individual character

:1,$d - delete all content of file

:w - Save the file but keep it open

:q - Quit without saving

:wq - Save the file and quit