diff --git a/tool/lib/output.rb b/tool/lib/output.rb
index 7db4e43881..25c6b47397 100644
--- a/tool/lib/output.rb
+++ b/tool/lib/output.rb
@@ -6,6 +6,7 @@ class Output
 
   def initialize
     @path = @timestamp = @ifchange = @color = nil
+    @overwrite = @create_only = false
     @vpath = VPath.new
   end
 
@@ -15,10 +16,12 @@ class Output
     opt.on('-t', '--timestamp[=PATH]') {|v| @timestamp = v || true}
     opt.on('-c', '--[no-]if-change') {|v| @ifchange = v}
     opt.on('--[no-]color') {|v| @color = v}
+    opt.on('--[no-]create-only') {|v| @create_only = v}
+    opt.on('--[no-]overwrite') {|v| @overwrite = v}
     @vpath.def_options(opt)
   end
 
-  def write(data, overwrite: false, create_only: false)
+  def write(data, overwrite: @overwrite, create_only: @create_only)
     unless @path
       $stdout.print data
       return true