mongo:tldr:385e5

mongo: Evaluate a JavaScript expression on the database.

mongo

$ mongo --eval '${JSON-stringify(db-foo-findOne())}' ${database}

try on your machine

This command is used to execute a JavaScript expression in the MongoDB shell. Here's a breakdown of the components:

mongo: This is the command to start the MongoDB shell.
--eval: It is a command-line option that specifies that the following argument should be evaluated as a JavaScript expression.
${JSON-stringify(db-foo-findOne())}: This is the JavaScript expression to be evaluated. In this case, it involves calling the db.foo.findOne() function, which searches for a single document in the "foo" collection of the current database. The result of this function call is then passed to JSON.stringify() to convert it to a JSON string.
${database}: This is a command line argument that represents the name of the database to connect to. The value of this argument is provided separately when executing the command.

So, when the command is executed, it connects to the specified database and evaluates the JavaScript expression to find and return a single document from the "foo" collection as a JSON string.

This explanation was created by an AI. In most cases those are correct. But please always be careful and never run a command you are not sure if it is safe.

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