2914feeb7e
It's a bit more pedantic regarding .Bl list elements. This has an added benefit of unbreaking the ipfw(8) manpage, where groff was silently skipping one list element.
151 lines
3.8 KiB
Groff
151 lines
3.8 KiB
Groff
.\" Copyright (c) 1980, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)getpriority.2 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD$
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.\"
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.Dd June 4, 1993
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.Dt GETPRIORITY 2
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.Os
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.Sh NAME
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.Nm getpriority ,
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.Nm setpriority
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.Nd get/set program scheduling priority
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/time.h
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.In sys/resource.h
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.Ft int
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.Fn getpriority "int which" "int who"
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.Ft int
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.Fn setpriority "int which" "int who" "int prio"
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.Sh DESCRIPTION
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The scheduling
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priority of the process, process group, or user, as indicated by
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.Fa which
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and
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.Fa who
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is obtained with the
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.Fn getpriority
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system call and set with the
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.Fn setpriority
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system call.
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The
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.Fa which
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argument
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is one of
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.Dv PRIO_PROCESS ,
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.Dv PRIO_PGRP ,
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or
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.Dv PRIO_USER ,
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and
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.Fa who
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is interpreted relative to
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.Fa which
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(a process identifier for
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.Dv PRIO_PROCESS ,
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process group
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identifier for
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.Dv PRIO_PGRP ,
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and a user ID for
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.Dv PRIO_USER ) .
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A zero value of
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.Fa who
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denotes the current process, process group, or user.
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The
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.Fa prio
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argument
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is a value in the range -20 to 20.
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The default priority is 0;
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lower priorities cause more favorable scheduling.
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.Pp
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The
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.Fn getpriority
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system call returns the highest priority (lowest numerical value)
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enjoyed by any of the specified processes.
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The
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.Fn setpriority
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system call sets the priorities of all of the specified processes
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to the specified value.
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Only the super-user may lower priorities.
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.Sh RETURN VALUES
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Since
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.Fn getpriority
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can legitimately return the value -1, it is necessary
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to clear the external variable
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.Va errno
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prior to the
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call, then check it afterward to determine
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if a -1 is an error or a legitimate value.
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.Pp
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.Rv -std setpriority
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.Sh ERRORS
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The
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.Fn getpriority
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and
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.Fn setpriority
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system calls
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will fail if:
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.Bl -tag -width Er
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.It Bq Er ESRCH
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No process was located using the
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.Fa which
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and
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.Fa who
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values specified.
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.It Bq Er EINVAL
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The
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.Fa which
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argument
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was not one of
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.Dv PRIO_PROCESS ,
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.Dv PRIO_PGRP ,
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or
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.Dv PRIO_USER .
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.El
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.Pp
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In addition to the errors indicated above,
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.Fn setpriority
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EPERM
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A process was located, but neither its effective nor real user
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ID matched the effective user ID of the caller.
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.It Bq Er EACCES
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A non super-user attempted to lower a process priority.
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.El
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.Sh SEE ALSO
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.Xr nice 1 ,
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.Xr fork 2 ,
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.Xr renice 8
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.Sh HISTORY
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The
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.Fn getpriority
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system call appeared in
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.Bx 4.2 .
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