Question: I jump around on various Mongodb databases and want to create  a process to programatically check the  Current USER. What is the MongoDB command to check the current user?

Answer:

Adding the connectionStatus details will give you formation about the current connection, specifically the state of authenticated users and their available permissions.

db.runCommand({connectionStatus : 1})

If you want to return extra information about the privileges , you can add the showPrivileges parameter, which will list out all the user privileges.

db.runCommand({connectionStatus : 1,showPrivileges:true})

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