renice Command
Intermediate Process Management man(1)Alter priority of running processes
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📅 Updated: Mar 15, 2026
SYNTAX
renice [OPTION]... PRIORITY PID...
What Does renice Do?
renice changes the scheduling priority (niceness) of running processes. While nice sets priority at launch time, renice modifies priority of processes that are already running.
renice can target processes by PID, by user (all processes of a user), or by process group. It is commonly used to lower the priority of runaway processes or to prioritize critical tasks without restarting them.
Niceness values range from -20 (highest priority) to 19 (lowest priority). Regular users can only increase niceness (lower priority). Only root can decrease niceness (increase priority).
renice can target processes by PID, by user (all processes of a user), or by process group. It is commonly used to lower the priority of runaway processes or to prioritize critical tasks without restarting them.
Niceness values range from -20 (highest priority) to 19 (lowest priority). Regular users can only increase niceness (lower priority). Only root can decrease niceness (increase priority).
Options & Flags
| Option | Description | Example |
|---|---|---|
| -n | Specify niceness value | renice -n 10 -p 1234 |
| -p | Target process by PID | renice -n 15 -p 1234 |
| -u | Target all processes of a user | sudo renice -n 10 -u www-data |
| -g | Target process group | renice -n 5 -g 1234 |
Practical Examples
#1 Lower process priority
Sets the process to low priority so it does not hog CPU.
$ renice -n 15 -p 1234
Output:
1234 (process ID) old priority 0, new priority 15
#2 Increase priority (root)
Gives a critical process higher priority.
$ sudo renice -n -5 -p 1234#3 Renice all user processes
Sets all of backupuser's processes to lowest priority.
$ sudo renice -n 19 -u backupuser#4 Fix runaway process
Drops the priority of a CPU-hogging process without killing it.
$ renice -n 19 -p $(pgrep -f "heavy_process")#5 Renice process group
Changes priority for all processes in the process group.
$ renice -n 10 -g 5678Tips & Best Practices
Quick priority fix: When a process is hogging CPU: renice -n 19 -p PID. This instantly makes it yield to other processes without killing it.
Cannot reverse as non-root: Regular users can increase niceness but cannot decrease it. Once you nice a process to 19, you need root to bring it back.
Use htop instead: htop lets you renice processes interactively: select process, press F7/F8 to change niceness. More convenient than command line.
Frequently Asked Questions
How do I change priority of a running process?
Use renice -n VALUE -p PID. Example: renice -n 10 -p 1234 sets niceness to 10.
Why does renice say "Permission denied"?
Regular users can only increase niceness (lower priority). Decreasing niceness (higher priority) requires root/sudo.
What is the difference between nice and renice?
nice sets priority when launching a new process. renice changes priority of an already running process.
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