How do I save a portion of the current buffer to a separate file?

Explanation

:w accepts a line range and a filename to write just those lines to a new file. This is useful for extracting a function, a config section, or any block of lines into its own file — without leaving Vim or doing any copy-paste.

How it works

• :{range}w {file} — write the lines in {range} to {file} (creates or overwrites)
• :{range}w >> {file} — append the lines to {file} instead
• Ranges can be line numbers, marks, or relative expressions:
  • :10,25w extract.py — write lines 10–25 to extract.py
  • :'a,'bw section.txt — write from mark a to mark b
  • :.,$w rest.txt — write from current line to end of file
  • :'<,'>w selection.txt — write the last visual selection (set automatically when you : in visual mode)

Example

In visual mode, select a block, then type : — Vim prepopulates :'<,'>. Complete it:

:'<,'>w /tmp/snippet.py

The selected lines are written to /tmp/snippet.py.

Append the current function to a log file:

:'{,'}w >> ~/notes/functions.log

Tips

• :w! to force-overwrite a read-only or existing file
• After writing a range, the original buffer is unchanged — this is a non-destructive operation
• Combine with :r to move text between buffers: write to /tmp/clip.txt in one buffer, :r /tmp/clip.txt in another
• To write the whole file to a different path (Save As), use :saveas {newfile} — it also renames the buffer