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.\" Copyright (c) 1996 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Paul Kranenburg.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by the NetBSD
.\" Foundation, Inc. and its contributors.
.\" 4. Neither the name of The NetBSD Foundation nor the names of its
.\" contributors may be used to endorse or promote products derived
.\" from this software without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.\" $NetBSD: psignal.9,v 1.1 1996/06/22 22:57:35 pk Exp $
.\" $FreeBSD$
.\"
.Dd June 22, 1996
.Dt PSIGNAL 9
.Os
.Sh NAME
.Nm psignal ,
.Nm pgsignal ,
.Nm gsignal
.Nd post signal to a process or process group
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <sys/signalvar.h>
.Ft void
.Fn psignal "struct proc *p" "int signum"
.Ft void
.Fn pgsignal "struct pgrp *pgrp" "int signum" "int checkctty"
.Ft void
.Fn gsignal "int pgid" "int signum"
.Sh DESCRIPTION
These functions post a signal to one or more processes. The argument
.Fa signum
common to all three functions should be in the range
.Bq 1- Ns Dv NSIG .
.Pp
The
.Fn psignal
function posts signal number
.Fa signum
to the process represented by the process structure
.Fa p .
With a few exceptions noted below, the target process signal disposition is
updated and is marked as runnable, so further handling of the signal is done
in the context of the target process after a context switch. Note that
.Fn psignal
does not by itself cause a context switch to happen.
.Pp
The target process is not marked as runnable in the following cases:
.Bl -bullet -offset indent
.It
The target process is sleeping uninterruptibly. The signal will be
noticed when the process returns from the system call or trap.
.It
The target process is currently ignoring the signal.
.It
If a stop signal is sent to a sleeping process that takes the
default action
.Pq see Xr sigaction 2 ,
the process is stopped without awakening it.
.It
.Dv SIGCONT
restarts a stopped process
.Pq or puts them back to sleep
regardless of the signal action
.Pq e.g., blocked or ignored .
.El
.Pp
If the target process is being traced
.Fn psignal
behaves as if the target process were taking the default action for
.Fa signum .
This allows the tracing process to be notified of the signal.
.Pp
The
.Fn pgsignal
function posts signal number
.Fa signum
to each member of the process group described by
.Fa pgrp .
If
.Fa checkctty
is non-zero, the signal will be posted only to processes that have
a controlling terminal.
.Fn pgsignal
is implemented by walking along the process list headed by the field
.Li pg_members
of the process group structure
pointed at by
.Fa pgrp
and calling
.Fn psignal
as appropriate. If
.Fa pgrp
is
.Dv NULL
no action is taken.
.Pp
The
.Fn gsignal
function posts signal number
.Fa signum
to each member of the process group identified by the group id
.Fa pgid .
.Fn gsignal
first finds the group structure associated with
.Fa pgid ,
then invokes
.Fn pgsignal
with the argument
.Fa checkctty
set to zero. If
.Fa pgid
is zero no action is taken.
.Sh SEE ALSO
.Xr sigaction 2 ,
.Xr tsleep 9
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