nice / renice

Updated

July 31, 2026

Overview

nice starts a process with an adjusted CPU niceness (priority bias). renice changes niceness of running processes. Range is typically -20 (highest priority) to 19 (lowest). Unprivileged users can only increase nice (make friendlier).

Syntax

nice [-n adjustment] command
renice [-n] priority [-p PID...] [-u user...]

Examples with Explanations

Start low priority

nice -n 19 ./batch-compress.sh
nice -n 10 tar -czf backup.tgz data/

Renice running

renice -n 15 -p 1234
sudo renice -n -5 -p 1234     # needs privilege for negative
renice -n 10 -u builduser

Inspect

ps -o pid,ni,comm -p 1234
top   # NI column

Notes

  • Niceness is not hard realtime priority (chrt/SCHED_FIFO).
  • I/O priority is separate (ionice on Linux).
  • Default nice is 0.