NICE(2)
NAME
nice − set program priority
SYNOPSIS
nice(incr)
DESCRIPTION
The scheduling priority of the process is augmented by incr. Positive priorities get less service than normal. Priority 10 is recommended to users who wish to execute long-running programs without flak from the administration.
Negative increments are ignored except on behalf of the super-user. The priority is limited to the range −20 (most urgent) to 20 (least).
The priority of a process is passed to a child process by fork(2). For a privileged process to return to normal priority from an unknown state, nice should be called successively with arguments −40 (goes to priority −20 because of truncation), 20 (to get to 0), then 0 (to maintain compatibility with previous versions of this call).
RETURN VALUE
Upon successful completion, nice returns 0.