How do I change the filename associated with the current buffer in Vim without saving to disk?

Explanation

:file {newname} (short form: :f {newname}) changes the filename Vim associates with the current buffer. The buffer's name in :ls, the status bar, and the % register all update immediately. The file on disk is not touched — the change is in-memory only. A subsequent :w will write to the new name.

How it works

• :file {newname} — set the buffer's filename to {newname}
• :file (no argument) — display the current filename (same as <C-g>)
• After renaming, the buffer is marked modified since it has not been saved under the new name
• The original file on disk is unaffected

Example

Create a nameless scratch buffer, assign it a path, then save:

:enew
" ... write some content ...
:file /tmp/notes.txt
:w

The buffer is now saved as /tmp/notes.txt. The original unnamed buffer is gone.

Tips

• Use :keepalt file {newname} to rename without overwriting the # (alternate file) register
• After :file {newname}, use :w to write, or :saveas {newname} which renames and writes in one step
• To rename the actual file on disk, use shell commands (:!mv old new) or a plugin like vim-eunuch
• Useful in scripts: assign a meaningful name to a scratch buffer before passing it to other commands