(BSD System Compatibility)

nice(3bsd)

nice -- (BSD) change priority of a process

Synopsis

   /usr/ucb/cc [flag . . . ] file . . .
   
   int nice(int 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 want to execute long-running programs without undue impact on system performance.

Negative increments are invalid, except when specified by the privileged user. The priority is limited to the range -20 (most urgent) to 20 (least). Requests for values above or below these limits result in the scheduling priority being set to the corresponding limit.

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 values

Upon successful completion, nice returns 0. Otherwise, a value of -1 is returned and errno is set to indicate the error.

The priority is not changed if:

EACCES: The value of incr specified was negative, and the effective user ID is not the privileged user.

References

fork(2), getpriority(3bsd), nice(1), priocntl(2), renice(1), renice(1Mbsd)