renice

Alter process scheduling priority

TLDR

Set the absolute priority of a running process

$ renice -n [3] -p [pid]

Increase the priority of a running process (requires root)

$ sudo renice -n [-4] -p [pid]

Decrease the priority of all processes owned by a user

$ renice -n [4] -u [user]

Set the priority of all processes in a process group

$ sudo renice -n [-5] -g [process_group]

SYNOPSIS

renice [-n] priority [-g|-p|-u] identifier...

renice alters the scheduling priority (niceness) of running processes. Niceness values range from -20 (highest priority, most favorable to the process) to 19 (lowest priority, least favorable).Regular users can only increase niceness (lower priority) of their own processes. The superuser can decrease niceness (raise priority) and modify any process.

PARAMETERS

-n priority

Specify the scheduling priority to set. Values range from -20 (highest) to 19 (lowest).

-p pid

Interpret arguments as process IDs (default).

-u user

Interpret arguments as usernames or UIDs.

-g pgrp

Interpret arguments as process group IDs.

CAVEATS

Lowering niceness (increasing priority) requires root privileges. The actual scheduling effect depends on the system's scheduler and load. Setting extreme priorities can impact system responsiveness.

HISTORY

The renice command originated in 4.0BSD and has been a standard Unix utility since. It complements the nice command, which sets priority when launching new processes.