152 lines
4.2 KiB
Groff
152 lines
4.2 KiB
Groff
.\" Copyright (c) 1996 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Paul Kranenburg.
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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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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
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.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $NetBSD: psignal.9,v 1.1 1996/06/22 22:57:35 pk Exp $
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.\" $FreeBSD$
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.\"
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.Dd October 8, 2011
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.Dt PSIGNAL 9
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.Os
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.Sh NAME
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.Nm psignal ,
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.Nm pgsignal ,
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.Nm gsignal ,
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.Nm tdsignal
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.Nd post signal to a thread, process, or process group
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.Sh SYNOPSIS
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.In sys/types.h
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.In sys/signalvar.h
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.Ft void
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.Fn psignal "struct proc *p" "int signum"
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.Ft void
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.Fn pgsignal "struct pgrp *pgrp" "int signum" "int checkctty"
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.Ft void
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.Fn gsignal "int pgid" "int signum"
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.Ft void
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.Fn tdsignal "struct thread *td" "int signum"
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.Sh DESCRIPTION
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These functions post a signal to a thread or one or more processes.
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The argument
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.Fa signum
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common to all three functions should be in the range
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.Bq 1- Ns Dv NSIG .
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.Pp
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The
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.Fn psignal
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function posts signal number
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.Fa signum
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to the process represented by the process structure
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.Fa p .
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With a few exceptions noted below, the target process signal disposition is
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updated and is marked as runnable, so further handling of the signal is done
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in the context of the target process after a context switch.
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Note that
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.Fn psignal
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does not by itself cause a context switch to happen.
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.Pp
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The target process is not marked as runnable in the following cases:
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.Bl -bullet -offset indent
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.It
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The target process is sleeping uninterruptibly.
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The signal will be
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noticed when the process returns from the system call or trap.
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.It
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The target process is currently ignoring the signal.
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.It
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If a stop signal is sent to a sleeping process that takes the
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default action
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(see
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.Xr sigaction 2 ) ,
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the process is stopped without awakening it.
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.It
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.Dv SIGCONT
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restarts a stopped process
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(or puts them back to sleep)
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regardless of the signal action
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(e.g., blocked or ignored).
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.El
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.Pp
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If the target process is being traced
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.Fn psignal
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behaves as if the target process were taking the default action for
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.Fa signum .
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This allows the tracing process to be notified of the signal.
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.Pp
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The
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.Fn pgsignal
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function posts signal number
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.Fa signum
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to each member of the process group described by
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.Fa pgrp .
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If
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.Fa checkctty
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is non-zero, the signal will be posted only to processes that have
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a controlling terminal.
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.Fn pgsignal
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is implemented by walking along the process list headed by the field
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.Li pg_members
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of the process group structure
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pointed at by
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.Fa pgrp
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and calling
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.Fn psignal
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as appropriate.
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If
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.Fa pgrp
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is
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.Dv NULL
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no action is taken.
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.Pp
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The
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.Fn gsignal
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function posts signal number
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.Fa signum
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to each member of the process group identified by the group id
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.Fa pgid .
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.Fn gsignal
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first finds the group structure associated with
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.Fa pgid ,
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then invokes
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.Fn pgsignal
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with the argument
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.Fa checkctty
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set to zero.
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If
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.Fa pgid
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is zero no action is taken.
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.Pp
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The
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.Fn tdsignal
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function posts signal number
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.Fa signum
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to the thread represented by the thread structure
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.Fa td .
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.Sh SEE ALSO
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.Xr sigaction 2 ,
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.Xr signal 9 ,
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.Xr tsleep 9
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