Replace: Same as with sed, Replace OLD with NEW:

Vi: Search and Replace

Change to normal mode with .

Search (Wraped around at end of file):

  Search STRING forward :   / STRING.   Search STRING backward:   ? STRING.    Repeat search:   n   Repeat search in opposite direction:  N  (SHIFT-n) 

Replace: Same as with sed, Replace OLD with NEW:

   First occurrence on current line:      :s/OLD/NEW     Globally (all) on current line:        :s/OLD/NEW/g    Between two lines #,#:                 :#,#s/OLD/NEW/g     Every occurrence in file:              :%s/OLD/NEW/g