How do I clear or empty a macro register in Vim?

Explanation

How it works

To clear a macro register, you simply start recording into that register and immediately stop. The command qaq breaks down as:

• qa -- start recording a macro into register a
• q -- stop recording immediately

Since no keystrokes were recorded between start and stop, register a is now empty. This effectively clears whatever was previously stored in that register.

This technique is particularly useful before using recursive macros. A recursive macro calls itself with @a at the end, and it will keep running until it encounters an error. If register a already contains old macro contents, a recursive macro might behave unexpectedly. Clearing the register first ensures a clean slate.

You can also clear a register using :let @a = '' in command mode, which has the same effect.

Example

Suppose you want to set up a recursive macro that deletes lines containing TODO:

1. First, clear register a: qaq
2. Now record the recursive macro: qa then /TODO then Enter then dd then @a then q
3. Run it with @a

The recursive macro will keep finding and deleting TODO lines until no more matches are found. Without clearing the register first, old contents could interfere with the recursion.