How do I edit an existing macro without re-recording it from scratch?

Explanation

When a recorded macro contains a typo or needs a small tweak, you can modify it directly via the :let command rather than re-recording the entire sequence. This is one of the most powerful macro debugging techniques available in Vim.

How it works

Vim stores macros in regular named registers. You can read and write these registers just like any other Vimscript variable:

1. Inspect the current macro with :echo @a or :reg a
2. Edit by assigning a new string: :let @a = 'new keystrokes'
3. Alternatively, paste-edit-yank: "ap to paste the macro onto a scratch line, edit it visually, then "ayy to yank the line back into register a

Special key sequences use Vim's internal notation and must be typed literally when using :let. For example, Enter is \n, Escape is \e, and <Ctrl-w> is \<C-w>.

The paste-edit-yank workflow is often more practical for complex macros:

" Paste macro a onto a new line to inspect it
"ap
" (edit the line visually)
" Yank it back into register a
"ayy
" Delete the scratch line
dd

Example

Suppose you recorded qa to add a semicolon to the end of a line and move down:

:echo @a
" Output: A;<Esc>j

You realize you also need to go to the beginning of the next line. Fix it without re-recording:

:let @a = 'A;<Esc>j0'

The macro is updated immediately — run it with @a.

Tips

• Use "ap on an empty line, edit, then V"ay to yank just the modified content (without the trailing newline)
• To save a macro permanently, put :let @a = '...' in your vimrc
• Uppercase register assignment (:let @A = 'extra') appends to register a rather than replacing it