Logstash could not be started because there is already another instance

Elastic Stack Logstash
5

The error that you have is:

 Logstash could not be started because there is already another instance using the configured data directory.

That is because you already have logstash running in the background as a service. We verified this using the systemctl status logstash command.
So if you want to run you command

sudo bin/logstash --path.settings /etc/logstash/ --path.data sensor39 -f /home/Data/syslog.conf

Then you will need to stop the already running logstash service. To stop the service you would run

systemctl stop logstash

That will stop the logstash service running in the background, which will allow you to run your logstash command.

I am assuming that you are just testing using the logstash command. Whenever you are done testing, you can just do

systemctl start logstash

To start the logstash service again.

You can only have 1 logstash running at a time pointing to the same data directory (/etc/logstash)

Also, if you are just testing, I would recommend adding this to your command

--config.reload.automatic
sudo bin/logstash --path.settings /etc/logstash/ --path.data sensor39 -f /home/Data/syslog.conf --config.reload.automatic

The reload.automatic will allow you to make live changes to your logstash configuration file without having to stop and start logstash to test.

I hope this helps.