NAME

nice − change priority of a process

SYNOPSIS

#include <unistd.h>

int nice(int incr);

DESCRIPTION

nice() allows a process to change its priority.  The invoking process must be in a scheduling class that supports the nice() system call.  The priocntl function is a more general interface to scheduler functions. 

nice() adds the value of incr to the nice value of the calling process.  A process’s nice value is a non-negative 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.  (The default nice value is 20.)  Requests for values above or below these limits result in the nice value being set to the corresponding limit. 

RETURN VALUES

Upon successful completion, nice() returns the new nice value minus 20.  Otherwise, a value of −1 is returned and errno is set to indicate the error. 

ERRORS

nice() fails if one or more of the following are true:

EINVAL nice() is called by a process in a scheduling class other than time-sharing. 

EPERM incr is negative or greater than 40 and the effective user id of the calling process is not super-user. 

SEE ALSO

nice(1), exec(2), priocntl(2)

SunOS 5.5.1  —  Last change: 08 Apr 1994