You can use the UNIX redirect and append operator (>>) with
w to append all or part
of the contents of the buffer to an existing file.
For example, if you entered:
:1,10wnewfile
and then:
$ |
|
|---|
newfile would contain lines 1-10 and line 340 to the end of the buffer.
- from O'Reilly & Associates' Learning the vi Editor, Chapter 5