NICE(3)

NAME
nice - set program scheduling priority

LIBRARY
libc

SYNOPSIS
#include <unistd.h>
int
nice(int incr);

DESCRIPTION
This interface is obsoleted by setpriority(2).

The nice() function obtains the scheduling priority of the process from the system and sets it to the priority value specified in incr. The priority is a value in the range -20 to 20. The default priority is 0; lower priorities cause more favorable scheduling. Only the super-user may lower priorities.

Children inherit the priority of their parent processes via fork(2).

RETURN VALUES
Upon successful completion, nice() returns the new nice value. Otherwise, -1 is returned, the process' nice value is not changed, and errno is set appropriately.

ERRORS
The nice() function will fail if:

[EPERM]
    The incr argument is negative and the calling process does not have super-user privileges.

SEE ALSO
nice(1), fork(2), setpriority(2), renice(8)

HISTORY
A nice() syscall appeared in AT&T UNIX.