git.saurik.com Git - apple/xnu.git/blame_incremental

... / ...

Commit	Line	Data
	1	.\" $NetBSD: getpriority.2,v 1.4 1995/02/27 12:33:15 cgd 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. All advertising materials mentioning features or use of this software
	15	.\" must display the following acknowledgement:
	16	.\" This product includes software developed by the University of
	17	.\" California, Berkeley and its contributors.
	18	.\" 4. Neither the name of the University nor the names of its contributors
	19	.\" may be used to endorse or promote products derived from this software
	20	.\" without specific prior written permission.
	21	.\"
	22	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	23	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	24	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	25	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	26	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	27	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	28	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	29	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	30	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	31	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	32	.\" SUCH DAMAGE.
	33	.\"
	34	.\" @(#)getpriority.2 8.1 (Berkeley) 6/4/93
	35	.\"
	36	.Dd June 4, 1993
	37	.Dt GETPRIORITY 2
	38	.Os BSD 4
	39	.Sh NAME
	40	.Nm getpriority ,
	41	.Nm setpriority
	42	.Nd get/set program scheduling priority
	43	.Sh SYNOPSIS
	44	.Fd #include <sys/time.h>
	45	.Fd #include <sys/resource.h>
	46	.Ft int
	47	.Fn getpriority "int which" "int who"
	48	.Ft int
	49	.Fn setpriority "int which" "int who" "int prio"
	50	.Sh DESCRIPTION
	51	The scheduling
	52	priority of the process, process group, or user, as indicated by
	53	.Fa which
	54	and
	55	.Fa who
	56	is obtained with the
	57	.Fn getpriority
	58	call and set with the
	59	.Fn setpriority
	60	call.
	61	.Fa Which
	62	is one of
	63	.Dv PRIO_PROCESS ,
	64	.Dv PRIO_PGRP ,
	65	or
	66	.Dv PRIO_USER ,
	67	and
	68	.Fa who
	69	is interpreted relative to
	70	.Fa which
	71	(a process identifier for
	72	.Dv PRIO_PROCESS ,
	73	process group
	74	identifier for
	75	.Dv PRIO_PGRP ,
	76	and a user ID for
	77	.Dv PRIO_USER ) .
	78	A zero value of
	79	.Fa who
	80	denotes the current process, process group, or user.
	81	.Fa Prio
	82	is a value in the range -20 to 20. The default priority is 0;
	83	lower priorities cause more favorable scheduling.
	84	.Pp
	85	The
	86	.Fn getpriority
	87	call returns the highest priority (lowest numerical value)
	88	enjoyed by any of the specified processes. The
	89	.Fn setpriority
	90	call sets the priorities of all of the specified processes
	91	to the specified value. Only the super-user may lower priorities.
	92	.Sh RETURN VALUES
	93	Since
	94	.Fn getpriority
	95	can legitimately return the value -1, it is necessary
	96	to clear the external variable
	97	.Va errno
	98	prior to the
	99	call, then check it afterward to determine
	100	if a -1 is an error or a legitimate value.
	101	The
	102	.Fn setpriority
	103	call returns 0 if there is no error, or
	104	-1 if there is.
	105	.Sh ERRORS
	106	.Fn Getpriority
	107	and
	108	.Fn setpriority
	109	will fail if:
	110	.Bl -tag -width Er
	111	.It Bq Er ESRCH
	112	No process was located using the
	113	.Fa which
	114	and
	115	.Fa who
	116	values specified.
	117	.It Bq Er EINVAL
	118	.Fa Which
	119	was not one of
	120	.Dv PRIO_PROCESS ,
	121	.Dv PRIO_PGRP ,
	122	or
	123	.Dv PRIO_USER .
	124	.El
	125	.Pp
	126	.Bl -tag -width Er
	127	In addition to the errors indicated above,
	128	.Fn setpriority
	129	will fail if:
	130	.It Bq Er EPERM
	131	A process was located, but neither its effective nor real user
	132	ID matched the effective user ID of the caller.
	133	.It Bq Er EACCES
	134	A 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
	141	The
	142	.Fn getpriority
	143	function call appeared in
	144	.Bx 4.2 .