J Join next line down to line with cursor. U Undo all changes to line with cursor. The undo and repeat commands u Use to undo the last command. . Use to repeat the last command. U Use to undo all chances on the current line.
P Put before the cursor the last item yanked or deleted.
Emphatic form of quit. ZZ Write and quit. Provides wrap margin at k characters from right. Tells you your current line number. Ctrl-L Clears the screen of system messages.