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.\" 30.Dd February 28, 2015 31.Dt NICE 3 32.Os 33.Sh NAME 34.Nm nice 35.Nd set program scheduling priority 36.Sh LIBRARY 37.Lb libc 38.Sh SYNOPSIS 39.In unistd.h 40.Ft int 41.Fn nice "int incr" 42.Sh DESCRIPTION 43.Bf -symbolic 44This interface is obsoleted by 45.Xr setpriority 2 . 46.Ef 47.Pp 48The 49.Fn nice 50function adds 51.Fa incr 52to the scheduling priority of the process. 53The priority is a value in the range -20 to 20. 54The default priority is 0; lower priorities cause more favorable scheduling. 55Only the super-user may lower priorities. 56.Pp 57Children inherit the priority of their parent processes via 58.Xr fork 2 . 59.Sh RETURN VALUES 60Upon successful completion, 61.Fn nice 62returns 0, and 63.Va errno 64is unchanged. 65Otherwise, \-1 is returned, the process' nice value is not changed, and 66.Va errno 67is set to indicate the error. 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 caller does not have appropriate 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 STANDARDS 84The 85.Fn nice 86function conforms to 87.St -p1003.1-2008 88except for the return value. 89This implementation returns 0 upon successful completion but 90the standard requires returning the new nice value, 91which could be \-1. 92.Sh HISTORY 93A 94.Fn nice 95syscall appeared in 96.At v6 . 97