What command is used to display the current user's ID?

The command used to display the current user's ID is "id." When executed, it provides information about the user ID (UID) and the group ID (GID) associated with the current user, as well as the groups to which the user belongs. This makes it particularly useful for understanding user permissions and roles within the system.

While "whoami" does provide the username of the current user, it does not display the numeric user ID. The commands "user" and "currentuser" are not standard Linux commands and would result in an error if attempted. Therefore, "id" is the command that most accurately fulfills the requirement of showing the current user's ID along with additional relevant information.