- add default stdin/stdout when necessary if the -e flag is used.

lib/logstash/agent.rb

@@ -73,6 +73,15 @@ class LogStash::Agent < Clamp::Command
 
     if @config_path
       @config_string = load_config(@config_path)
+    else
+      # include a default stdin input if no inputs given
+      if @config_string !~ /input *{/
+        @config_string += "input { stdin { } }"
+      end
+      # include a default stdout output if no outputs given
+      if @config_string !~ /output *{/
+        @config_string += "output { stdout { codec => rubydebug } }"
+      end
     end
 
     begin