To replace a single letter with another letter, position the cursor over the letter and type the r command, followed by the replacement letter. For example, to replace the ``u'' in ``rub'' by ``i'', move the cursor to the ``u'' and enter ri.
To replace an unlimited amount of text with new text, position the cursor over the first letter and type R. You are now in replace mode. This functions like insertion mode, but characters you type will replace the previously existing text until you return to command mode by pressing <Esc>. For example, to convert ``needle'' into ``noodle'', move the cursor onto the first ``e'' and enter Roo<Esc>.
Use the ~ command to switch letters between uppercase and lowercase text. First place the cursor over the character to be switched.
Join two lines by typing the command J. The line
below the cursor is joined to the end of the current line. Any
leading spaces on the lower line are replaced by a single one.
Once more unto
This produces the line:
Once more unto the breach