What does "WARNING: not changing user" mean in Neo4j?

Question

When I try to start my Neo4j database on Ubuntu 14.04, I see a message: WARNING: not changing user. What does this mean, is it important and how do I overcome the warning?

The warning doesn't stop the server from starting.

Full output:

adam@ubuntu:~$ sudo service neo4j-service start
Using additional JVM arguments:  -server -XX:+DisableExplicitGC - Dorg.neo4j.server.properties=conf/neo4j-server.properties -Djava.util.logging.config.file=conf/logging.properties -Dlog4j.configuration=file:conf/log4j.properties -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -XX:-OmitStackTraceInFastThrow
Starting Neo4j Server...WARNING: not changing user
process [3699]... waiting for server to be ready..... OK.
http://localhost:7474/ is ready.

Answer 1

The (badly worded) warning is telling you that you are not starting neo4j as the root user. When running neo4j in production, one would normally expect the root user to start neo4j.

But during development, most people probably run neo4j on their local computer under their own user id -- and this should not be a problem.

Also, note that neo4j uses the UID environment variable to determine the current user ID. At least in my case, echo $UID and sudo echo $UID return the same value. Therefore, you will still see the warning even if you use sudo to start neo4j. However, if I use su to become the root user, echo $UID returns 0 (the root user ID), and neo4j will not display the warning.