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: src/lib/libc/sys/getpriority.2,v 1.4.2.5 2001/12/14 18:34:00 ru Exp $ 34.\" $DragonFly: src/lib/libc/sys/getpriority.2,v 1.2 2003/06/17 04:26:47 dillon Exp $ 35.\" 36.Dd June 4, 1993 37.Dt GETPRIORITY 2 38.Os 39.Sh NAME 40.Nm getpriority , 41.Nm setpriority 42.Nd get/set program scheduling priority 43.Sh LIBRARY 44.Lb libc 45.Sh SYNOPSIS 46.In sys/time.h 47.In sys/resource.h 48.Ft int 49.Fn getpriority "int which" "int who" 50.Ft int 51.Fn setpriority "int which" "int who" "int prio" 52.Sh DESCRIPTION 53The scheduling 54priority of the process, process group, or user, as indicated by 55.Fa which 56and 57.Fa who 58is obtained with the 59.Fn getpriority 60call and set with the 61.Fn setpriority 62call. 63.Fa Which 64is one of 65.Dv PRIO_PROCESS , 66.Dv PRIO_PGRP , 67or 68.Dv PRIO_USER , 69and 70.Fa who 71is interpreted relative to 72.Fa which 73(a process identifier for 74.Dv PRIO_PROCESS , 75process group 76identifier for 77.Dv PRIO_PGRP , 78and a user ID for 79.Dv PRIO_USER ) . 80A zero value of 81.Fa who 82denotes the current process, process group, or user. 83.Fa Prio 84is a value in the range -20 to 20. The default priority is 0; 85lower priorities cause more favorable scheduling. 86.Pp 87The 88.Fn getpriority 89call returns the highest priority (lowest numerical value) 90enjoyed by any of the specified processes. The 91.Fn setpriority 92call sets the priorities of all of the specified processes 93to the specified value. Only the super-user may lower priorities. 94.Sh RETURN VALUES 95Since 96.Fn getpriority 97can legitimately return the value -1, it is necessary 98to clear the external variable 99.Va errno 100prior to the 101call, then check it afterward to determine 102if a -1 is an error or a legitimate value. 103.Pp 104.Rv -std setpriority 105.Sh ERRORS 106.Fn Getpriority 107and 108.Fn setpriority 109will fail if: 110.Bl -tag -width Er 111.It Bq Er ESRCH 112No process was located using the 113.Fa which 114and 115.Fa who 116values specified. 117.It Bq Er EINVAL 118.Fa Which 119was not one of 120.Dv PRIO_PROCESS , 121.Dv PRIO_PGRP , 122or 123.Dv PRIO_USER . 124.El 125.Pp 126.Bl -tag -width Er 127In addition to the errors indicated above, 128.Fn setpriority 129will fail if: 130.It Bq Er EPERM 131A process was located, but neither its effective nor real user 132ID matched the effective user ID of the caller. 133.It Bq Er EACCES 134A non super-user attempted to lower a process priority. 135.El 136.Sh SEE ALSO 137.Xr nice 1 , 138.Xr fork 2 , 139.Xr renice 8 140.Sh HISTORY 141The 142.Fn getpriority 143function call appeared in 144.Bx 4.2 . 145