How do I quickly switch between multiple graphs without modifying neo4j.conf?

If you have multiple graphs set up and want to quickly switch between each without modifying dbms.active_database in conf/neo4j.conf,
you can accomplish this with a neo4j restart and with the environment variable NEO4J_CONF defined pointing to the appropriate/corresponding neo4j.conf file.

For example, one could define:

$NEO4J_HOME/conf
$NEO4J_HOME/conf_test

and where each directory has the same files, namely:

jmx.access  jmx.password  neo4j.conf  neo4j-wrapper.conf

and in the $NEO4J_HOME/conf_tests/neo4j.conf one might configure the databse name to a different graph:

# The name of the database to mount
dbms.active_database=graph.db.test

Then, prior to a restart of neo4j if one modifies the environment variable NEO4J_CONF to point to the $NEO4J_HOME/conf_test, for
example:

export NEO4J_CONF="/home/neo/neo4j-enterprise-3.0.7/conf_test"

then upon restart of neo4j, it will then use the graph in the graph.db.test location.

Note: Be aware that the dbms.active_database setting in neo4j.conf is one of many settings that you may want/need to change.
If for example you do not change #dbms.directories.logs=logs then both conf files will result in each Neo instance
writing to $NEO4J_HOME/logs.