Which command is used in Linux to check the current users logged into a system?

The command used in Linux to check the current users logged into a system is "who." This command displays a list of users currently logged in, along with additional information such as the terminal they are using and the time of their login. It's a fundamental command for system administrators and users to monitor active sessions and understand who is accessing the system at any given time.

The "users" command, while it does provide a list of logged-in users, is a simpler version that only outputs the usernames without additional context. The commands "current" and "active" are not standard commands in Linux for this purpose and would not return the information regarding currently logged-in users. Therefore, "who" is the most comprehensive and widely used choice for identifying active system users.