Vi Text Editor My Frequently Used Commands

h              move cursor one character to left
j              move cursor one line down
k              move cursor one line up
l              move cursor one character to right
w              move cursor one word to right
b              move cursor one word to left
0              move cursor to beginning of line
$              move cursor to end of line
nG             move cursor to line n
1G             move cursor to 1st line
G              move cursor to last line
control-f      scroll forward one screen
control-b      scroll backward one screen

gx             jump to method definition

zi             switch folding on or off
za             toggle current fold open/closed
zc             close current fold
zR             open all folds
zM             close all folds
zv             expand folds to reveal cursor

i              insert to left of current cursor position (end with ESC)
a              append to right of current cursor position (end with ESC)
dw             delete current word (end with ESC)
cw             change current word (end with ESC)
r              change current character
~              change case (upper-, lower-) of current character

dd             delete current line
D              delete portion of current line to right of the cursor
x              delete current character
dgg            delete current line to the top of the file
jdG            delete all lines below current line
ma             mark currrent position
d`a            delete everything from the marked position to here
`a             go back to the marked position
p              dump out at current place your last deletion (``paste'')

u              undo the last command 
.              repeat the last command 

J              combine (``join'') next line with this one

:w             write file to disk, stay in vi
:q!            quit VI, do not write file to disk,
ZZ             write file to disk, quit vi

:r filename    read in a copy of the specified file to the current
               buffer

/string        search forward for string (end with Enter)
?string        search backward for string (end with Enter)
n              repeat the last search (``next search'')
N              repeat the last search backward
/\cstring      case insensitive prepend with \c

:s/s1/s2       replace (``substitute'') (the first) s1 in this line by s2
:lr/s/s1/s2/g  replace all instances of s1 in the line range lr by s2
               (lr is of form 'a,b', where a and b are either explicit
               line numbers, or . (current line) or $ (last line)
:map k s       map the key k to a string of vi commands s (see below)
:abb s1 s2     expand the string s1 in append/insert mode to a string 
               s2 (see below)
%              go to the "mate," if one exists, of this parenthesis
               or brace or bracket (very useful for programmers!)

:%s/foo/bar/g  replace every 'foo' with a 'bar'
:!command      execute a command from vi
:%!perltidy    format perl code using perltidy from within vi
:%!perltidy -l=0    ignore line length 
:noh           remove search highlighting
:sp            to split window horizontally
:vsp           to split window vertically
<ctrl-w>h|j|k|l to navigate between split windows
<ctrl-w>q      to quit split window 

Comment/Uncomment:
Press Ctrl+V and go down until the last commented line and press x, that will delete all the # characters vertically.

For commenting a block of text is almost the same: First, go to the first line you want to comment, press Ctrl+V, and select until the last line. Second, press Shift+I, then #, then Esc.

Indent several lines at once:
Press Ctrl+V and go down until the last line to be indented, press Shift+>

Cut/Copy and Paste:
Position the cursor where you want to begin cutting.
Press v (or upper case V if you want to cut whole lines).
Move the cursor to the end of what you want to cut.
Press d to cut or y to copy.
Move to where you would like to paste.
Press P to paste before the cursor, or p to paste after.
Copy and paste can be performed with the same steps, only pressing y instead of d in step 4.
The name of the mark used is related to the operation (d:delete or y:yank).