1.\" Copyright (c) 1980, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)nice.3 8.1 (Berkeley) 6/4/93 29.\" $FreeBSD: src/lib/libc/gen/nice.3,v 1.6.2.4 2001/12/14 18:33:51 ru Exp $ 30.\" $DragonFly: src/lib/libc/gen/nice.3,v 1.2 2003/06/17 04:26:42 dillon Exp $ 31.\" 32.Dd June 25, 2009 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. 65Otherwise, -1 is returned, the process' nice value is not changed, and 66.Va errno 67is set appropriately. 68.Sh ERRORS 69The 70.Fn nice 71function will fail if: 72.Bl -tag -width Er 73.It Bq Er EPERM 74The 75.Fa incr 76argument is negative and the calling process does not have super-user privileges. 77.El 78.Sh SEE ALSO 79.Xr nice 1 , 80.Xr fork 2 , 81.Xr setpriority 2 , 82.Xr renice 8 83.Sh HISTORY 84A 85.Fn nice 86syscall appeared in 87.At v6 . 88