1.\" $NetBSD: nice.3,v 1.13 2003/08/07 16:42:53 agc Exp $ 2.\" 3.\" Copyright (c) 1980, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)nice.3 8.1 (Berkeley) 6/4/93 31.\" 32.Dd February 16, 1998 33.Dt NICE 3 34.Os 35.Sh NAME 36.Nm nice 37.Nd set program scheduling priority 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In unistd.h 42.Ft int 43.Fn nice "int incr" 44.Sh DESCRIPTION 45.Bf -symbolic 46This interface is obsoleted by 47.Xr setpriority 2 . 48.Ef 49.Pp 50The 51.Fn nice 52function obtains the scheduling priority of the process 53from the system and sets it to the priority value specified in 54.Fa incr . 55The priority is a value in the range -20 to 20. 56The default priority is 0; lower priorities cause more favorable scheduling. 57Only the super-user may lower priorities. 58.Pp 59Children inherit the priority of their parent processes via 60.Xr fork 2 . 61.Sh RETURN VALUES 62Upon successful completion, 63.Fn nice 64returns the new nice value minus 65.Dv NZERO . 66Otherwise, \-1 is returned, the process' nice value is not changed, and 67.Va errno 68is set to indicate the error. 69.Sh ERRORS 70The 71.Fn nice 72function will fail if: 73.Bl -tag -width Er 74.It Bq Er EPERM 75The 76.Fa incr 77argument is negative and the caller is not the super-user. 78.El 79.Sh SEE ALSO 80.Xr nice 1 , 81.Xr fork 2 , 82.Xr setpriority 2 , 83.Xr renice 8 84.Sh STANDARDS 85The 86.Fn nice 87function conforms to 88.St -xpg4.2 . 89.Sh HISTORY 90A 91.Fn nice 92syscall appeared in 93.At v6 . 94