HP-UX Reference (11i v2 03/08) - 2 System Calls (vol 5)

nice(2) nice(2)

NAME

nice - change priority of a process

SYNOPSIS

#include <unistd.h>

int nice(int priority_change);

DESCRIPTION

nice() adds the value of priority_change to the nice value of the calling process. A process’s nice value

is a positive number for which a more positive value results in lower CPU priority.

A maximum nice value of 39 and a minimum nice value of 0 are imposed by the system. Requests for

values above or below these limits result in the nice value being set to the corresponding limit.

If the calling process contains more than one thread or lightweight process (i.e., the process is multi-

threaded) this function shall apply to all threads or lightweight processes in the calling process.

RETURN VALUE

Upon successful completion,

nice() returns the new nice value minus 20. Otherwise, a value of −1is

returned and

errno is set to indicate the error.

Note that

nice() assumes a user process priority value of 20. If a user having appropriate privileges

has changed the user process priority value to something less than 20, certain values for priority_change

can cause nice() to return −1, which is indistinguishable from an error return.

ERRORS

[EPERM]

nice() fails and does not change the nice value if priority_change is negative or greater

than 40, and the effective user ID of the calling process is not a user having appropriate

privileges.