Entering the vi
prompt$ vi
prompt$ vi file1 file2 …
prompt$ vi -r file #Recover file from crash
prompt$ vi +string file #Execute ex command “string”
prompt$ vi @rcfile #Read commands from rcfile
Insert/Overtype Mode

Insert/Overtype Mode is solely for entering text. To leave one of these two modes press the [ESC] key. if you wish to enter the ESC character or any other control character while in insert mode: type [CONTROL]-V and then the control sequence. The only difference between Insert Mode and Overtype Mode is that characters are placed in front of the text after the cursor in Insert Mode, where as existing characters are overwritten in Overtype Mode.
Command Mode
Entering Insert Mode
a append text, after the cursor
i insert text, before the cursor
R enter Overtype Mode
A append text, after end of line
I insert text, before first non-whitespace character
o open new line below cursor in Insert Mode
O open new line above cursor in Insert Mode
vi Syntax

vi commands follow the general form:
n operator m object
which means:
execute operator n times on m objects. If n and/or m are omitted, they default to 1.
Operators which take objects are(if the operator is pressed twice then the object is the current line)
c Change
d Deletion
“cy Yank, if “c is omitted, uses general buffer.
< shift lines left by shiftwidth variable
> shift lines right by shiftwidth variable
!cmd filter trough cmd
#The operators <, >, and ! are line based so the set of objects is diminished greatly.
Operators which do not take objects:
s Substitute
x Delete character
r Replace character
~ change case of character
Objects (if given without an operator are interpreted as a cursor motion command):
w forward until beginning of word
e forward until end of word
b backward until beginning of word
$ forward until end of line
^ backward until first non-whitespace character
0 backward until first column of line
nG line number n. (default: $, i.e. last line of file)
n| column n of current line
/pat forward until beginning of pat, search
?pat backward until beginning of pat, backward search
n repeat last search
N repeat last search/backward search, but in opposite direction
% until match of parenthesis, brace, or bracket
tc until next appearance of c on current line
Tc backward until next appearance of c on current line
fc until and including next appearance of c on current line
Fc backward until and including next appearance of c on current line
; repeat last f, F, t, or T
, repeat last f, F, t, or T in reverse
} forward until end of paragraph
{ backward until end of paragraph
) forward until end of sentence
( backward until end of sentence
]] forward until end of section
[[ backward until end of section
nH n lines before first line on screen; n defaults to 0
nL n lines before last line on screen; n defaults to 0
M the middle line of the screen
j down one line
k up one line
h left one character
l right one character
[BS] left one character, backspace usually equals ^H
[SPACE] right one character
_ the entire current line
- until first non-whitespace character on previous line
+ until first non-whitespace character on next line
[RETURN] until first non-whitespace character on next line

Miscellaneous¹
u undo last change
U undo entire line
“cp put “c or general buffer after the cursor
“cP put “c or general buffer before the cursor
mc set mark with character c
`c goto mark c
‘c goto beginning of line with mark c
“ return to position before mark jump or search
” return to beginning of line before mark jump or search
J join two lines
D delete rest of line
C change rest of line
Y yank current line into general buffer
& execute last ex-style substitution
. execute last modification
!obj cmd send object as stdin to command and replace with stdout
[Ctrl]-G print information about file
: map x y when character x is pressed, execute y
: map! x y map input mode character x to string y
: ab x y x is an abbreviation for y, changes are made on the fly
: su Suspend the current editor session
: sh run a shell
ex Commands
ex syntax

ex commands in the vi follow this general form:
: addr command
which means:
Execute command on specific lines obtained from the address part of the general form. If address is omitted, current line is used. Keep in mind that the ex is a line based editor, so all actions are line based.
addresses:
% all lines in file
x,y lines x to y
. current line
n line number: n
$ last line of file
x-n n lines before line x
x+n n lines after line x
/pat/ forward to line containing pat
?pat? backward to line containing pat
Some commands are:
refer to ex manual page for more commands
s/pat/text/ substitute 1st match of pat with text
s/pat/text/g substitute every match of pat with text
s/pat/text/n substitute the nth occurrence of pat with text
ya c yank into buffer c or the general buffer if c is omitted
g address cmd execute cmd on all lines which satisfy address
> shift right
< shift left
d delete line
! UNIX-cmd execute UNIX-cmd on line
m address move lines to address

The vi environment variables

set
You can customize your environment with this command by typing set var=value, this will set the specified var to value for a scalar variable. For boolean variables, use set var to set and set novar to unset. You can see which variables are set by just typing the set by its self. You can see a list of all variables by typing set all. Some environment variables are specific to the ex editor and some are specific to the vi editor. I have included both.

(I am missing some variables, please contact me with additions.)
boolean variables:
autoindent(ai) begin editing next line at same level of indent-ion as this one.
autowrite(aw) write current buffer before leaving
exrc(ex) tells vi/ex if it should read the .exrc file in the current directory(this can be a security risk).
errorbells editor sends a beep to the terminal when an incorrect
flash inverse the screen on an error instead of producing a bell
ignorecase(ic) ignore case of characters in searches.
lisp enter lisp mode
list place a $ at the end of each line and a ^I on each tab.
magic allow ., [, and * to be interpreted as special characters in RE's.
modelines execute the first and last 5 lines of the file if of the form: ex:command: or vi:command:
number(nu) number lines in left margin
showmatch(sm) when closing a paren., brace or bracket; move the visual cursor to opening item to check scope
showmode(smd) show type of insert mode
wrapscan(ws) when searching and at bottom of file, continue searching from the top
scalar variables:
directory the location of the temporary directory used by vi
paragraphs(para) macros to signify the beginning of a paragraph
report vi will notify you if you change more lines than the value of report
sections(sect) macros to signify the beginning of a section
shell The shell to use when executing the command :sh or :!
shiftwidth(sw) number of spaces to to insert on a shift operation
showmatch(sm) show the match of ) and } when typed
tabstop the length, in characters, of a tabstop
term holds the name of the terminal type being used
wrapmargin(wm) split lines at the column which is equal to the value of wrapmargin
File Saving and Loading
: wq write file and quit
: w write file
: w file write to specified file
: w! overwrite existing file
: e file edit new file
: r file put contents of file
: q quit the editor
: q! force quit the editor, do not save changes
: x quit the editor, save file if it was modified
ZZ quit the editor, save file if it was modified
: n start editing next file in list
: rew rewind file list, start editing 1st file on argument list again
Q quit vi and enter ex
: pre Preserve file.
: rec file recover file
Examples²
j move cursor down
k move cursor up
h or [BS] move cursor left
l or [SPACE] move cursor right
+ or [RETURN] first non-whitespace character on next line
cw change word
dd or d_ delete line
yy or y_ yank current line into the general buffer
"ayj yank current line and one below into buffer a
yfc yank until next occurrence of c on current line into the general buffer
3dl or d3l delete next 3 characters
4c( or 2c2( or c4( change next 4 sentences
>% while on a brace, paren., or bracket; shift right until closing brace, etc.
:%!sort or :1,$!sort sort current file
:5,10s/foo/bar/2 change the second occurrence of foo with bar on lines 5-10
:map g 1G map g to really run 1G
3J Join next 2 lines to current one
3,9m$ move lines 3 through 9 to the end of the file
ab w/o without when w/o is typed change to without
:?foo?,/bar/d delete from the reverse match of foo until the next match of bar
:g/{/,/}/< shift all lines between, and including, a “{” and a “}” left
:$-4,$d delete last five lines of buffer
:%s/^\(.*\) \(.*\)$/\2 \1/ swap everything before and after the first space
d” delete from current position to line of last jump