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NICE(P) 			    POSIX Programmer's Manual				  NICE(P)

NAME
       nice - change the nice value of a process

SYNOPSIS
       #include <unistd.h>

       int nice(int incr);

DESCRIPTION
       The  nice() function shall add the value of incr to the nice value of the calling process.
       A process' nice value is a non-negative number for  which  a  more  positive  value  shall
       result in less favorable scheduling.

       A  maximum nice value of 2*{NZERO}-1 and a minimum nice value of 0 shall be imposed by the
       system. Requests for values above or below these limits shall result  in  the  nice  value
       being set to the corresponding limit. Only a process with appropriate privileges can lower
       the nice value.

       Calling the nice() function has no effect on the priority of  processes	or  threads  with
       policy  SCHED_FIFO  or  SCHED_RR. The effect on processes or threads with other scheduling
       policies is implementation-defined.

       The nice value set with nice() shall be applied to the process.	If the process is  multi-
       threaded, the nice value shall affect all system scope threads in the process.

       As  -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 whether errno is non-zero.

RETURN VALUE
       Upon successful completion, nice() shall return the new nice value -{NZERO}. Otherwise, -1
       shall be returned, the process' nice value shall not be changed, and errno shall be set to
       indicate the error.

ERRORS
       The nice() function shall fail if:

       EPERM  The  incr  argument  is  negative and the calling process does not have appropriate
	      privileges.

       The following sections are informative.

EXAMPLES
   Changing the Nice Value
       The following example adds the value of the incr argument, -20, to the nice value  of  the
       calling process.

	      #include <unistd.h>
	      ...
	      int incr = -20;
	      int ret;

	      ret = nice(incr);

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       getpriority() , setpriority() , the Base Definitions volume of IEEE Std 1003.1-2001, <lim-
       its.h>, <unistd.h>

COPYRIGHT
       Portions of this text are reprinted and	reproduced  in	electronic  form  from	IEEE  Std
       1003.1,	2003  Edition,	Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  by
       the  Institute  of  Electrical  and  Electronics Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE  and  The  Open  Group
       Standard, the original IEEE and The Open Group Standard is the referee document. The orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003					  NICE(P)
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