There may be several good sources of information about vi or its clones already residing in your computer. One of them is the vi manual pages, which are accessed by typing
Another is the help files, which can be accessed while vi is in use by typing
Vim comes with a tutorial which is stored in text form in a directory such as /usr/share/vim/vim61/. After confirming the exact location on your system, you can navigate to that directory and open the file with a command such as
This assumes that the tutorial is named "tutor" in your system. The "cat" command is used to open the tutorial in read-only mode. The "|" and the "more" are standard Unix commands that work together to display a long file one page at a time for easier reading.
nvi comes with a tutorial which is stored as a compressed file in /usr/doc/nvi/. This file can be accessed by copying it to your home directory, uncompressing it and then opening it with vi. For example, from your home directory type:
An advanced tutorial is also available in the same directory.
There is also a substantial amount of material about vi and its clones online. Some of the more useful sites are presented here: