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Name

nice - change priority of a process

Synopsis

/usr/ucb/cc [ flag ... ] file ...

int nice(incr)
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.

See Also

nice(1) , renice(1) , fork(2) , priocntl(2) , getpriority(3C)

Notes

Use of these interfaces should be restricted to only applications written on BSD platforms. Use of these interfaces with any of the system libraries or in multi-thread applications is unsupported.

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