BufEnter

BufEnter is an autocommand event in Vim and Neovim that fires when a buffer becomes the active buffer in a window. It runs after the buffer is shown in the current window, and it is commonly used to apply buffer-local options, initialize state, or trigger actions that should occur whenever you switch to that buffer.

Related events include BufWinEnter and BufLeave. BufWinEnter fires when a window displaying a buffer becomes active, which can happen when you move between windows. BufEnter, by contrast, is specifically about the buffer becoming the active buffer in the current window, regardless of whether you have just changed windows or switched buffers within the same window.

Typical usage involves defining autocommands that adjust behavior on a per-buffer basis. For example, you might set buffer-local options when entering certain file types, such as changing indentation for Python files or enabling line wrapping for Markdown files. Examples include setting tab width for Python buffers or enabling wrap for text-oriented files, all scoped to the buffers that match a pattern.

Because BufEnter can fire frequently as you navigate between buffers, it is common to limit commands with filetype or filename patterns, or to scope commands to the <buffer> to avoid affecting other buffers unintentionally. Proper scoping helps keep behavior predictable and efficient as you switch among multiple open buffers.

See also BufLeave and BufWinEnter for related lifecycle events, as well as general autocommand usage and per-buffer configuration practices.

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