The Wildmenu

wildmenu, wildmode, wildoptions — making Tab at the : prompt actually pleasant.

Keys: Tab, Shift-Tab, Ctrl-N, Ctrl-P

Three options shape Tab completion at the : prompt. wildmenu turns on the visual menu; wildmode picks the cycling strategy; wildoptions tweaks behavior. Together they turn : into a tolerable file picker.

By default, vintage Vim's Tab completion at the : prompt just replaces what you typed with the first match, with no preview of the alternatives. Tab again cycles. It works, but you're guessing. Three options turn this into a real menu.

Option	What it does
`wildmenu`	Turns on the visual completion menu — a list of candidates above the `:` line that you can walk through with `Tab`/`Shift-Tab` (or `Ctrl-N`/`Ctrl-P`).
`wildmode`	How `Tab` behaves: complete to longest common prefix first, cycle, list-only, or some combination.
`wildoptions`	Extra wildmenu features. The most useful value is `pum` (Neovim 0.9+): show completions as a popup menu over the buffer rather than a single-line strip.

The recipe everyone copies

These four lines in your config buy you a competent file picker without any plugin:

set wildmenu
set wildmode=longest:full,full
set wildoptions+=pum
set wildignorecase

Read it as: show the menu, on the first Tab complete to the longest unambiguous prefix and open the menu, on the second Tab cycle through entries; render the menu as a popup (Neovim only); be case-insensitive for filename matching.

A worked example

Suppose your cwd contains README.md, render_html.py, render_markdown.py, and requirements.txt. With the recipe above:

Keystrokes	What you see
`:e rTab`	Command-line becomes `:e re`; the menu lists every matching file: `README.md`, `render_html.py`, `render_markdown.py`, `requirements.txt`.
`Tab`	Command-line becomes `:e README.md`; first menu entry highlighted.
`Tab`	Advances to `:e render_html.py`.
`Tab`	`:e render_markdown.py`.
`nTab`	Type `n` to extend the prefix to `ren`, then `Tab` again — menu narrows to just the two `render_*` files.
`Enter`	Opens the highlighted file.