Usage:
 renice [-n|--priority|--relative] <priority> [-p|--pid] <pid>...
 renice [-n|--priority|--relative] <priority>  -g|--pgrp <pgid>...
 renice [-n|--priority|--relative] <priority>  -u|--user <user>...

Alter the priority of running processes.

Options:
 -n <num>               specify the 'absolute' nice value,
                          but 'relative' when POSIXLY_CORRECT is set
 --priority <num>       specify the 'absolute' nice value
 --relative <num>       specify the 'relative' nice value
 -p, --pid              interpret arguments as process ID (default)
 -g, --pgrp             interpret arguments as process group ID
 -u, --user             interpret arguments as username or user ID

 -h, --help             display this help
 -V, --version          display version

For more details see renice(1).