renice [priority] [options] [target]

Control the scheduling priority of running processes. May be applied to a process, process group, or user (target). A privileged user may alter the priority of other users' processes. priority must, for ordinary users, lie between 0 and the environment variable PRIO_MAX (normally 20), with a higher number indicating increased niceness. A higher niceness value means that the process will run at a lower priority. A privileged user may set a negative priority, as low as PRIO_MIN (normally -20), to speed up processes. See the nice command for setting the scheduling priority for processes when they are initially run.