How can I check if MongoDB has been started?

There are several ways to determine if MongoDB has started:

1. To start MongoDB, use the command line and enter the “mongo” command. If you successfully connect to the MongoDB server and enter the MongoDB command line interface, it means that MongoDB has been started.
2. To view the log files of MongoDB, you can usually find them in the directory /var/log/mongodb. You can use the tail command to view the latest log file. If you see log information like [initandlisten] waiting for connections, it means that MongoDB has been started.
3. To check the MongoDB process, you can use the ‘ps’ command to see if the MongoDB process is running. For example, running the command ‘ps aux | grep mongod’ will show if a process named ‘mongod’ is running.
4. Management tools for MongoDB: MongoDB offers some management tools such as MongoDB Compass and MongoDB Shell, which can be used to connect to the MongoDB server and view the server’s status information. If you are able to successfully connect and view the relevant information, it indicates that MongoDB is already running.

No matter which method is used, as long as the MongoDB server can be successfully connected to or relevant logs or process information can be viewed, it can be confirmed that MongoDB has started.