How to test if MongoDB database exists on command line (bash)

Use this command to test if a given MongoDB database exists:

mongo --quiet --eval 'db.getMongo().getDBNames().indexOf("mydb")'

This will return an index such as 0 or 241 if the database is found. On the other hand, it will return -1 if the database does not exist.

docker-compose version:

docker-compose exec mongodb mongo --quiet --eval 'db.getMongo().getDBNames().indexOf("mydb")'

where mongodb is the name of your container.

Now we can put it together in a bash script to test if the database exists:

# Query if DB exists in MongoDB
mongo_indexof_db=$(mongo --quiet --eval 'db.getMongo().getDBNames().indexOf("mydb")')
if [ $mongo_indexof_db -ne "-1" ]; then
    echo "MongoDB database exists"
else
    echo "MongoDB database does not exist"
fi

docker-compose variant:

# Query if DB exists in MongoDB
mongo_indexof_db=$(docker-compose -f inspect.yml exec -T mongodb mongo --quiet --eval 'db.getMongo().getDBNames().indexOf("mydb")')
if [ $mongo_indexof_db -ne "-1" ]; then
    echo "MongoDB database exists"
else
    echo "MongoDB database does not exist"
fi