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. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)getpriority.2 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD$ 34.\" 35.Dd June 4, 1993 36.Dt GETPRIORITY 2 37.Os 38.Sh NAME 39.Nm getpriority , 40.Nm setpriority 41.Nd get/set program scheduling priority 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In sys/time.h 46.In sys/resource.h 47.Ft int 48.Fn getpriority "int which" "int who" 49.Ft int 50.Fn setpriority "int which" "int who" "int prio" 51.Sh DESCRIPTION 52The scheduling 53priority of the process, process group, or user, as indicated by 54.Fa which 55and 56.Fa who 57is obtained with the 58.Fn getpriority 59call and set with the 60.Fn setpriority 61call. 62.Fa Which 63is one of 64.Dv PRIO_PROCESS , 65.Dv PRIO_PGRP , 66or 67.Dv PRIO_USER , 68and 69.Fa who 70is interpreted relative to 71.Fa which 72(a process identifier for 73.Dv PRIO_PROCESS , 74process group 75identifier for 76.Dv PRIO_PGRP , 77and a user ID for 78.Dv PRIO_USER ) . 79A zero value of 80.Fa who 81denotes the current process, process group, or user. 82.Fa Prio 83is a value in the range -20 to 20. The default priority is 0; 84lower priorities cause more favorable scheduling. 85.Pp 86The 87.Fn getpriority 88call returns the highest priority (lowest numerical value) 89enjoyed by any of the specified processes. The 90.Fn setpriority 91call sets the priorities of all of the specified processes 92to the specified value. Only the super-user may lower priorities. 93.Sh RETURN VALUES 94Since 95.Fn getpriority 96can legitimately return the value -1, it is necessary 97to clear the external variable 98.Va errno 99prior to the 100call, then check it afterward to determine 101if a -1 is an error or a legitimate value. 102.Pp 103.Rv -std setpriority 104.Sh ERRORS 105.Fn Getpriority 106and 107.Fn setpriority 108will fail if: 109.Bl -tag -width Er 110.It Bq Er ESRCH 111No process was located using the 112.Fa which 113and 114.Fa who 115values specified. 116.It Bq Er EINVAL 117.Fa Which 118was not one of 119.Dv PRIO_PROCESS , 120.Dv PRIO_PGRP , 121or 122.Dv PRIO_USER . 123.El 124.Pp 125.Bl -tag -width Er 126In addition to the errors indicated above, 127.Fn setpriority 128will fail if: 129.It Bq Er EPERM 130A process was located, but neither its effective nor real user 131ID matched the effective user ID of the caller. 132.It Bq Er EACCES 133A non super-user attempted to lower a process priority. 134.El 135.Sh SEE ALSO 136.Xr nice 1 , 137.Xr fork 2 , 138.Xr renice 8 139.Sh HISTORY 140The 141.Fn getpriority 142function call appeared in 143.Bx 4.2 . 144