nice and renice: Linux Process Priority

The "niceness" of a process is a numeric hint to the kernel about how the process should be treated in relation to other processes contending for the CPU. The strange name is derived from the fact that it determines how nice you are going to be to other users of the system. A high nice value means a low priority for your process: you are going to be nice. A low or negative value means high priority: you are not very nice. The range of allowable niceness values is -20 to +19.