[address
]w
[!
] [[>>
]file
]
Write lines specified by address
to file
,
or write full contents of buffer if address
is not specified.
If file
is also omitted, save the contents of the buffer
to the current filename.
If >> file
is used, write contents to the end of an existing
file
. The ! flag forces the editor to write over any current
contents of file
.