How do I prevent Vim from adding a newline at the end of a file when saving?

Explanation

By default, Vim enforces POSIX compliance by appending a final newline to any file that lacks one. The fixendofline option (enabled by default) controls this behavior. Setting :set nofixendofline disables it, so Vim writes the file exactly as its buffer represents it — no newline added.

This matters when editing files that must not gain a trailing newline: certain binary protocols, embedded data files, legacy formats, or repos with strict no-newline-at-end lint rules.

How it works

• fixendofline (default on) — if the buffer lacks a final newline, Vim adds one at write time
• :set nofixendofline — disables this; the file is written byte-for-byte as buffered
• You can also toggle it with :set noeol (the older alias) or check the current state with :set fixendofline?

Example

A file ends with data and no trailing newline. To keep it that way:

:set nofixendofline
:write

With the option off, :write no longer silently appends \n. You can verify with :set eol? — a value of noeol confirms the buffer has no final newline.

Tips

• Put set nofixendofline in an autocmd for specific file extensions: autocmd BufRead *.bin set nofixendofline
• Pair with :set binary to open binary files without Vim's text-mode transformations
• In Neovim, you can check vim.bo.fixendofline from Lua
• The opposite — ensuring a final newline — is achieved with :set fixendofline (the default)