nice(3B)

NAME

nice − 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 wish to execute long-running programs without undue impact on system performance.

Negative increments are illegal, 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.

ERRORS

The priority is not changed if:

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

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