syntax

$ ionice -c <scheduling class> -n <priority value> <options><command>

To set process with PID 89 as an idle I/O process

$ ionice -c 3 -p 89

To run bash program with highest priority.

$ ionice -c 2 -n 0 bash

To Print the class and priority of the processes with PID 89 and 91.    

$ ionice -p 89 91

$ ionice -p <PID1> <PID2>

regards,

T.Dhanasekar