For example, on *nix using the watch command:
$ watch /sbbs/exec/node list
Every 2.0s: /sbbs/exec/node list Synchronet Node Display/Control Utility v1.22 Node 1: User #1 posting message via telnet (MP) [U] Node 2: Waiting for connection Node 3: Waiting for connection Node 4: Waiting for connection Node 5: Waiting for connection Node 6: Waiting for connection Node 7: Waiting for connection Node 8: Waiting for connection Node 9: Waiting for connection Node 10: Waiting for connection