Wide area networks are often very wide, and installing or troubleshooting remote routers often requires fingers on keyboards in more than one physical location. Getting a listing of the users logged into a router is simple, which makes it easier to send that user a message (as many remote locations have no cell phone signal).
To list the users logged into a router, issue this command:
The output will show something like the following:
Line User Host(s) Idle Location
* 0 con 0 00:00:00
66 vty 0 qmchenry idle 00:13:49 trx3845a
The line starting with the asterisk is the session from which you run the command.