Check the status of specific (if arguments given) or all nodes in the system. For example:

bash-2.05b$ diagnose -n .0
diagnosing node table (5120 slots)
Name                    State  Procs     Memory         Disk          Swap      Speed  Opsys   Arch Par   Load Res Classes                        Network                        Features              

.0                       Busy   0:2     1912:2020     1961:1961     1961:1961    2.40 [NONE] [NONE] DEF   0.00 002 [Interactive_0:2][Batch_0:2]   [2]                            [NONE]              
WARNING:  node '.0' is active for 00:22:11 but load is LOW.  load:  0.000 (check job 0730214524.742248?)
-----                     ---   0:2     1912:2020     1961:1961     1961:1961  

Total Nodes: 1  (Active: 1  Idle: 0  Down: 0)