code: function putFile(req, res) {
  		var rest = req.params["0"];
  		var file = fileUtil.getFile(req, rest);
  		var fileRoot = options.fileRoot;
  		if (req.params['parts'] === 'meta') {
  			// TODO implement put of file attributes
  			return sendStatus(501, res);
  		}
  		function write() {
  			var ws = fs.createWriteStream(file.path);
  			ws.on('finish', function() {
  				fileUtil.withStatsAndETag(file.path, function(error, stats, etag) {
  					if (error && error.code === 'ENOENT') {
  						return writeResponse(404, res);
  					}
  					writeFileMetadata(fileRoot, req, res, file.path, stats, etag);
  				});
  			});
  			ws.on('error', function(err) {
  				writeError(500, res, err);
  			});
  			req.pipe(ws);
  		}
  		var ifMatchHeader = req.headers['if-match'];
  		fileUtil.withETag(file.path, function(error, etag) {
  			if (error && error.code === 'ENOENT') {
  				writeResponse(404, res);
  			}
  			else if (ifMatchHeader && ifMatchHeader !== etag) {
  				writeResponse(412, res);
  			}
  			else {
  				write();
  			}
  		});
  	}
docs: For file save.