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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 in-
       voking  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 de-
       fault value of 20. Requests for values above or below these limits  re-
       sult  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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