Where can I find rubydebug output

stdout {
 codec => rubydebug
 }

TIA

Your description is a bit basic, so I'm not sure if this is your config. Assuming you have a valid

input and filter config part, your output should look something like this:

output {
  stdout { codec => rubydebug }
}

The above example will give you a ruby debug output on your console.

If you would rather write it to file you can do it like this:

output {
 file {
   path => /tmp/my_output_text_file
   codec => rubydebug
 }
}

If you start your config with service logstash start your output might end up in /var/log/upstart/

Thanks for your input. But when I run, there's no console. Maybe I should look on the log of the logstash.