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nice(2)				 System	Calls			       nice(2)

NAME
       nice - change priority of a process

SYNOPSIS
       #include	<unistd.h>

       int nice(int incr);

DESCRIPTION
       The  nice()  function  allows  a	 process  to change its	priority.  The
       invoking	 process must be in  a	scheduling  class  that	 supports  the
       nice().

       The  nice()  function  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 greater positive	value results in lower CPU priority.

       A  maximum  nice	 value of (2 * NZERO) -1 and a minimum nice value of 0
       are imposed by the system.  NZERO  is  defined  in  <limits.h>  with  a
       default	value  of  20. Requests	for values above or below these	limits
       result in the nice value	being set to the corresponding limit.  A  nice
       value of	40 is treated as 39.

       Calling	the nice() function has	no effect on the priority of processes
       or threads with policy SCHED_FIFO or SCHED_RR.

       Only a process with the {PRIV_PROC_PRIOCNTL} privilege  can  lower  the
       nice value.

RETURN VALUES
       Upon  successful	 completion,  nice()  returns the new nice value minus
       NZERO. Otherwise, -1 is returned,  the  process's  nice	value  is  not
       changed,	and errno is set to indicate the error.

ERRORS
       The nice() function will	fail if:

       EINVAL	The  nice()  function  is  called by a process in a scheduling
		class other than time-sharing or fixed-priority.

       EPERM	The incr argument is negative  or  greater  than  40  and  the
		{PRIV_PROC_PRIOCNTL}  privilege	 is not	asserted in the	effec-
		tive set of the	calling	process.

USAGE
       The priocntl(2) function	is a more general interface to scheduler func-
       tions.

       Since  -1  is  a	permissible return value in a successful situation, an
       application wishing to check for	error situations should	set  errno  to
       0,  then	 call  nice(),	and if it returns -1, check to see if errno is
       non-zero.

ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE	TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Async-Signal-Safe		   |
       +-----------------------------+-----------------------------+

SEE ALSO
       nice(1),	exec(2), priocntl(2), getpriority(3C),	attributes(5),	privi-
       leges(5), standards(5)

SunOS 5.10			  1 Apr	2004			       nice(2)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | USAGE | ATTRIBUTES | SEE ALSO

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