Basic Introduction to the vi Editor
               http://www.seas.gwu.edu/~csci51/intro-vi.txt
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COMMAND                  COMMENT                                EXAMPLES
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vi filename              editor                                 vi file1
   i                        insert before cursor
   a                        add after cursor
   R                        replace
   o                        open new line below cursor
   O                        open new line above cursor
   esc ******************** exit insert mode ***************************
   arrow keys               cursor movement
   x                        delete this character
   dw                       delete this word
   [n]dd                    delete line(s)                      3dd
   p                        paste delete-buffer
   control-f                page forward
   control-b                page backward
   control-u                1/2 page up
   control-d                1/2 page down
   :set number              display with line numbers
   :set nonumber            return to no line numbers
   :n                       move cursor to line n               :149
   :$                       move cursor to end of file
   /                        search forward for string           /BEGIN
                               n gives next occurence
   ?                        search backward for string          ?LOOP
                               n gives next occurence
   :w                       write to file                       :w myfile
   :q!                      quit vi without writing
   :1,$ s/st1/st2/g         replaces all occurences of st1 by st2
   ZZ                       write and quit
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