Turning line numbers on and off is useful here: see Toggle Line Numbers on and off.
The title of this entry is somewhat misleading: this Vim Tip will definitely allow you to repeat an action on a section of a file, but it will also allow you to repeat any Normal Mode action. The dot command (
.) allows you to repeat your last Normal Mode action. I've spent years doing
j.j.j.j.j. to repeat a change on several lines. But there's an easier way:
:15,20normal . . That means "execute the Normal Mode dot command on lines 15 through 20." This also works on a visual selection:
:'<,'>normal .. And it's not limited to the dot command. If you wanted to add a ';' to the end of every line in a function, just get the line numbers and do:
:72,91normal A;. The
A; part of that command temporarily enters Insert Mode, but Vim automatically switches back to Normal mode after it's done so we don't have to tell it to hit