Saving Changes and Quitting vi
vi is rich in substantively synonymous commands that control the save of the buffer contents to a file and the exit from vi. These commands give you the option of saving, saving-and-quitting, or quitting-without-saving.
Save the contents of the buffer (write the buffer to the file on disk) by typing:
Saving and Quitting
Save and quit by typing:
Press Return. Alternatively, type ZZ.
Note that the command ZZ is neither preceded by a colon nor followed by Return.
Quitting Without Saving
When you've made no changes to a file and want to quit, type:
Press Return. If you have made changes, vi does not let you quit with :q. Instead, it displays the following message.
No write since last change (:quit! overrides)
If you do not want to save your changes, type: