OPTIONS -c, --class class Specify the name or number of the scheduling class to use; 0 for none, 1 for realtime, 2 for best-effort, 3 for idle. -n, --classdata level Specify the scheduling class data. This only has an effect if the class accepts an argument. For real-time and best-effort, 0-7 are valid data (priority levels).
# nice -n 19 ionice -c 2 -n 7 COMMAND
# ionice -p 27367 unknown: prio 4 # ionice -c 3 -p 27367 # ionice -p 27367 idle # # ionice -c 2 -p 27367 # ionice -p 27367 best-effort: prio 4 #