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.
Specify number by which to increase current priority of process, rather than an absolute priority number.
Specify number by which to decrease current priority of process, rather than an absolute priority number.
Interpret target parameters as process group IDs.
Adjust the priority by the value of increment, which is a positive or negative integer.
Interpret target parameters as process IDs (default).