diff --git a/summarizeMD b/summarizeMD
index 7ee042e..c426db5 100755
--- a/summarizeMD
+++ b/summarizeMD
@@ -7,7 +7,7 @@ require 'optparse/time'
 require 'ostruct'
 require 'yaml'
 
-VERSION = "0.1.0"
+VERSION = "0.2.0"
 
 class MDUtils
 
@@ -24,11 +24,9 @@ class MDUtils
 		puts "Generating summary for file " + filename
 
 		# In order to be sure to not write on existing file
-		timeNow = Time.now.to_f
-		tmpfilename = "tmp_00_" + timeNow.inspect + ".md"
-		temp_file = File.new(tmpfilename, "w")
+		temp_file = Tempfile.new("summarizeMd")
 
-		summary = "\#Summary \n\n"
+		summary = generate_sumary_heading(options)
 		forbidden_words = ['Table of contents', 'define', 'pragma']
 
 		File.open(filename, 'r') do |f|
@@ -49,27 +47,79 @@ class MDUtils
 			 		temp_file.puts line
 			 	end   
 		   	end
-
-			temp_file.close
-			summary += "  \n\n"
-			outputFilename = "summarized_" + filename
-			if !options.output.empty? 
-				outputFilename = options.output
-				outputComponents = outputFilename.split(".")
-
-				if outputComponents.last.downcase != "md" 
-					outputFilename += ".md"
-					if options.verbose 
-				    	puts "Forcing adding extension."
-				    end
-				end
-				
-			end
-			system("echo \"#{summary}\" | cat - #{tmpfilename} > #{outputFilename}")
-		    system("rm #{tmpfilename}")
-		    puts "Done.\n"
+                        temp_file.close
 		end
-	end #(end summarize)	
+                summary += "  \n\n"
+        
+                with_output_file(options, filename) do |output_file|
+                    if (options.replace_summary_token.empty?)
+                        prepend_to_file(summary, temp_file, output_file) 
+                    else
+                        replace_token_with(options.replace_summary_token, summary, temp_file, output_file)
+                    end
+                end
+                
+                temp_file.unlink
+                puts "Done.\n"
+	end #(end summarize)
+        
+        def self.prepend_to_file(toPrepend, source_file, target_file)
+            File.open(target_file, 'w') do |fo|
+                fo.puts(toPrepend)
+                File.foreach(source_file) do |li|
+                    fo.puts li
+                end
+            end
+        end
+        
+        def self.replace_token_with(token, toPrepend, source_file, target_file)
+            File.open(target_file, 'w') do |fo|
+                File.foreach(source_file) do |li|
+                    if li.include?(token)
+                        fo.puts toPrepend
+                    else
+                        fo.puts li
+                    end
+                end
+            end
+        end
+        
+        def self.with_output_file(options, filename)
+            outputFilename = "summarized_" + filename
+            if !options.output.empty? 
+                outputFilename = options.output
+                outputComponents = outputFilename.split(".")
+                if outputComponents.last.downcase != "md" 
+                    outputFilename += ".md"
+                    if options.verbose 
+                        puts "Forcing adding extension."
+                    end
+                end
+            end
+            
+            if File.file?(outputFilename) && !options.force
+                puts "output file exists. Use --force or -f to overwrite it."
+                exit 1
+            elsif File.directory?(outputFilename)
+                puts "output file cannot be a directory"
+                exit 2
+            else
+               File.open(outputFilename, "w") do |output_file|
+                  yield output_file 
+               end
+            end
+        end
+        
+        def self.generate_sumary_heading(options)
+            if options.heading_level == 0
+                return String.new
+            else
+                heading = String.new
+                options.heading_level.times { heading << "\#" }
+                heading << " Summary \n\n"
+                return heading
+            end
+        end
 
 end
 
@@ -87,7 +137,10 @@ class OptparseSummarize
     options = OpenStruct.new
     options.encoding = "utf8"
     options.verbose = false
+    options.force = false
     options.output = String.new
+    options.replace_summary_token = String.new
+    options.heading_level = 1
 
     opt_parser = OptionParser.new do |opts|
       opts.banner = "Usage: summarizeMD <filename> [options]"
@@ -100,27 +153,48 @@ class OptparseSummarize
               "Specify output filename") do |out|
         options.output << out
       end
+      
+      opts.on("-t", "--replace_summary_token [summary_token]",
+              "Replace the line containing the supplied token, with the sumrmary, instead of putting the summary in the top of the file. If the token is not found, then no summary is inserted.") do |out|
+        options.replace_summary_token << out
+      end
+      
+      opts.on("-l", "--heading_level [heading level]", Integer,
+              "Specify the heading level, eg. The number of ## to insert before the Sumary heading. Set this to 0 to not add a heading to the summary.") do |l|
+        options.heading_level = l
+      end
 
       # Boolean switch.
       opts.on("-v", "--[no-]verbose", "Run verbosely") do |v|
         options.verbose = v
       end
+      
+      # Boolean switch.
+      opts.on("-f", "--[no-]force", "force writing the output file, even if its overwrite an existing file") do |f|
+        options.force = f
+      end
 
       opts.separator ""
       opts.separator "Common options:"
 
       # No argument, shows at tail.  This will print an options summary.
       # Try it and see!
-      opts.on_tail("-h", "--help", "Show this message") do
+      opts.on("-h", "--help", "Show this message") do
         puts opts
         exit
       end
 
       # Another typical switch to print the version.
-      opts.on_tail("--version", "Show version") do
+      opts.on("--version", "Show version") do
         puts "#{VERSION}"
         exit
       end
+      
+      opts.separator ""
+      opts.separator "Exit codes:"
+      opts.separator "    1 = output file exists, and called without --force (-f)"
+      opts.separator "    2 = output file cannot be a directory"
+      opts.separator "    3 = --heading_level (-l) must be a positive integer or zero"
     end
 
     opt_parser.parse!(args) 
@@ -134,6 +208,10 @@ end  # class OptparseExample
 
 
 options = OptparseSummarize.parse(ARGV)
+if options.heading_level < 0
+    puts "--heading_level (-l) must be a positive integer or zero"
+    exit 3
+end
 
 mdUtils = MDUtils.summarize([ARGV[0], options]);