How do I autocomplete Vim command names and their arguments while in insert mode?

Explanation

The <C-x><C-v> key sequence in insert mode triggers Vim command-line completion — the same completion engine used at the : command prompt. This lets you type a partial Vim command and get a completion menu right inside your buffer, which is invaluable when editing .vim files, init.vim, or any Vimscript source.

How it works

• <C-x> enters the sub-completion menu (part of Vim's completion sub-mode)
• <C-v> selects the command-line completion provider
• Vim looks at the word before the cursor and suggests matching Ex commands, options, function names, and their arguments

The completion menu behaves identically to the : command line, including support for options after set, event names after autocmd, and arguments for any built-in command.

Example

While editing your init.vim, you type:

set comple

Pressing <C-x><C-v> opens a completion menu offering:

set complete
set completefunc
set completeopt
set completeslash

Select with <C-n> / <C-p> and press <Enter> or any key to confirm.

Tips

• Useful in any file, not only Vimscript — for example, completing shell command names if shell-related options are typed
• After completing a command, pressing <C-x><C-v> again will advance to argument completion, mirroring what happens on the actual command line
• Works alongside omnifunc and other completions; press <C-n> inside the popup to navigate