Transaction code SM04 shows the list of the users which are logged on to the instance in which are currently logged in. The total number of users and sessions are given at the bottom of the list.
User logged on to server (SAP user name).
Terminal at which the user is working. (If it is a UNIX front end, the terminal name corresponds to the display variable of the front end process; if it is a Windows or OS/2 front end, the terminal name corresponds to the host name on which the front end was started.)
Last executed SAP transaction code.
Time at which the user last initiated a dialog step by entering data.
Number of external sessions (session) opened by the user (up to 6). You can display detailed information on a session by selecting a user and choosing the Sessions button.
Connection type (GUI, RFC or Plugin (HTTP or SMTP request).
Size of the memory allocated to the user in megabytes.