Transaction code AL08 shows the list of all the users who are logged on to the system globally or for all the instances in the system which are active.
• Active instance
Shows the Active instance.
• Active users
Displays the active users logged on to the active instance.
• Interactive users
Displays the Dialog users logged on to the active instance.
• RFC users
Display the users that are connected via RFC on the active instance.
User name of users logged on.
From which Terminal/machine user has logged on.
Last executed transaction code.
The time when a user last initiated a dialog step by entering data.
• External Sessions
Number of External sessions the user has opened. It use SAP memory to share data between external sessions and it based on per main window. An external session is started when starting a program and when ever the use of CALL TRANSACTION. Each user can open maximum 6 SAP system windows in a single SAPGUI session. Each of these windows corresponds to a session on the application server with its own area of shared memory. The session can be created by System -> Create Session.
• Internal Sessions
Number of Internal sessions the user has opened. A session that with in external session. There can be many internal sessions in an external session. ABAP MEMORY is used to exchange the data between internal sessions. When calling a program using SUBMIT or CALL Transaction, it will be loaded in a new internal session.
You can get the same result by executing transaction code RSUSR000.