330 lines
8.2 KiB
Groff
330 lines
8.2 KiB
Groff
.\" $OpenBSD: init.8,v 1.50 2018/01/16 15:57:51 cheloha Exp $
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.\" $NetBSD: init.8,v 1.6 1995/03/18 14:56:31 cgd Exp $
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.\"
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.\" 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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.\" This code is derived from software contributed to Berkeley by
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.\" Donn Seeley at Berkeley Software Design, Inc.
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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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.\" 3. 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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.\" @(#)init.8 8.6 (Berkeley) 5/26/95
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.\"
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.Dd $Mdocdate: January 16 2018 $
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.Dt INIT 8
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.Os
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.Sh NAME
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.Nm init
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.Nd process control initialization
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.Sh SYNOPSIS
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.Nm init
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.Op Fl fs
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.Sh DESCRIPTION
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The
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.Nm
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program
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is the last stage of the boot process.
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It normally executes the sequence of events described in
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.Xr rc 8
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and begins multi-user operation.
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.Pp
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The kernel may pass the following options to
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.Nm ,
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usually when requested by the
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.Xr boot 8
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program:
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.Bl -tag -width Ds
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.It Fl f
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Activate fastboot mode.
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This is not currently supported by the
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.Ox
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kernel.
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Instead, use the
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.Pa /fastboot
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file as explained in the
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.Xr rc 8
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manual.
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.It Fl s
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Boot directly into single-user mode.
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.El
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.Pp
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Single-user mode is also entered if the boot scripts fail.
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.Pp
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In single-user mode, the
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.Xr rc 8
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script is not run and normal daemons are not started,
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but instead a super-user shell is started on the system console.
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If the
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.Ar console
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entry in the
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.Xr ttys 5
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file does not contain the
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.Dq secure
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flag, then
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.Nm
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will require that the superuser password be
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entered before the system will start a single-user shell.
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The password check is skipped if the
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.Ar console
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is marked as
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.Dq secure .
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.Pp
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In single-user mode, the system is quiescent for maintenance work and may
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later be made to go to multi-user by exiting the
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single-user shell (with ^D).
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This
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causes
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.Nm
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to run the
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.Xr rc 8
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startup command file in fastboot mode (skipping disk checks).
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.Pp
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The kernel
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.Xr securelevel 7
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is normally set to 0 while in single-user mode, and raised to 1 when
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the system begins multi-user operations.
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This action will not take
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place if the securelevel is \-1, and can be modified via the
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.Pa /etc/rc.securelevel
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script.
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.Pp
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In multi-user operation,
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.Nm
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maintains
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processes for the terminal ports found in the file
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.Xr ttys 5 .
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.Nm
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reads this file, and executes the command found in the second field.
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This command is usually
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.Xr getty 8 ;
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.Em getty
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opens and initializes the tty line
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and
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executes the
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.Em login
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program.
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The
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.Em login
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program, when a valid user logs in,
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executes a shell for that user.
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When this shell dies, either because the user logged out
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or an abnormal termination occurred (a signal),
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the
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.Nm
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program wakes up, deletes the user
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from the
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.Xr utmp 5
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file of current users and records the logout in the
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.Em wtmp
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file.
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The cycle is
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then restarted by
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.Nm
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executing a new
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.Em getty
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for the line.
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.Pp
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Line status (on, off, secure, getty, or window information)
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may be changed in the
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.Em ttys
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file without a reboot by sending the signal
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.Dv SIGHUP
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to
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.Nm
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with the command
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.Dq Li "kill \-s HUP 1" .
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On receipt of this signal,
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.Nm
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re-reads the
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.Em ttys
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file.
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When a line is turned off in
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.Em ttys ,
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.Nm
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will send a
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.Dv SIGHUP
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signal to the controlling process
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for the session associated with the line.
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For any lines that were previously turned off in the
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.Em ttys
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file and are now on,
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.Nm
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executes a new
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.Em getty
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to enable a new login.
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If the getty or window field for a line is changed,
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the change takes effect at the end of the current
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login session (e.g., the next time
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.Nm
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starts a process on the line).
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If a line is commented out or deleted from
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.Em ttys ,
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.Nm
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will not do anything at all to that line.
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However, it will complain that the relationship between lines
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in the
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.Em ttys
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file and records in the
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.Em utmp
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file is out of sync,
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so this practice is not recommended.
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.Pp
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.Nm
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will terminate multi-user operations and resume single-user mode
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if sent a terminate
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.Pq Dv TERM
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signal, for example,
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.Dq Li "kill \-s TERM 1" .
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If there are processes outstanding that are deadlocked (because of
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hardware or software failure),
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.Nm
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will not wait for them all to die (which might take forever), but
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will time out after 30 seconds and print a warning message.
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.Pp
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.Nm
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will cease creating new
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.Xr getty 8
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and allow the system to slowly die away, if it is sent a terminal stop
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.Pq Dv TSTP
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signal, i.e.,
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.Dq Li "kill \-s TSTP 1" .
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A later hangup will resume full
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multi-user operations, or a terminate will start a single-user shell.
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This hook is used by
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.Xr reboot 8
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and
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.Xr halt 8 .
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.Pp
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.Nm
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will terminate multi-user operations, kill all
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.Xr getty 8 ,
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and run
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.Pa /etc/rc.shutdown
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if a user-defined signal 1
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.Pq Dv USR1 ,
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user-defined signal 2
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.Pq Dv USR2 ,
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or interrupt
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.Pq Dv INT
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signal is received.
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Following this,
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.Dv USR1
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will halt the system;
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.Dv USR2
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will request a powerdown; and
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.Dv INT
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will cause a reboot.
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.Pa /etc/rc.shutdown
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can specify that a powerdown is requested instead of the action
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specified by the signal.
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.Pp
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The role of
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.Nm
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is so critical that if it dies, the system will reboot itself
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automatically.
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If, at bootstrap time, the
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.Nm
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process cannot be located, the system will panic with the message
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.Dq panic: "init died (signal %d, exit %d)" .
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.Sh RESOURCES
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When
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.Nm
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spawns a process it sets the process priority, umask, and resource
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limits based on
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.Pa /etc/login.conf .
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When starting the
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.Xr rc 8
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files, the login class
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.Dq daemon
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is used.
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When starting a window system or
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.Xr getty 8 ,
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the login class
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.Dq default
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is used.
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No resource changes are made when entering single-user mode.
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.Sh FILES
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.Bl -tag -width /etc/rc.securelevel -compact
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.It Pa /dev/console
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system console device
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.It Pa /dev/tty*
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terminal ports found in
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.Em ttys
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.It Pa /etc/rc
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system startup commands
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.It Pa /etc/rc.securelevel
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commands that run before the security level changes
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.It Pa /etc/rc.shutdown
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script run at shutdown time
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.It Pa /etc/ttys
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terminal initialization information file
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.It Pa /fastboot
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tells
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.Xr rc 8
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not to run
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.Xr fsck 8
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during the next boot
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.It Pa /var/run/utmp
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record of users currently logged in
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.It Pa /var/log/wtmp
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record of all logins and logouts
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.El
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.Sh DIAGNOSTICS
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.Bl -diag
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.It "getty repeating too quickly on port %s, sleeping"
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A process being started to service a line is exiting quickly
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each time it is started.
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This is often caused by a ringing or noisy terminal line.
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.Em "Init will sleep for 30 seconds" ,
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.Em "then continue trying to start the process" .
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.It "some processes would not die; ps axl advised."
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A process
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is hung and could not be killed when the system was shutting down.
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This condition is usually caused by a process
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that is stuck in a device driver because of
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a persistent device error condition.
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.El
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.Sh SEE ALSO
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.Xr kill 1 ,
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.Xr login 1 ,
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.Xr sh 1 ,
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.Xr fbtab 5 ,
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.Xr login.conf 5 ,
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.Xr ttys 5 ,
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.Xr securelevel 7 ,
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.Xr crash 8 ,
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.Xr getty 8 ,
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.Xr halt 8 ,
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.Xr rc 8 ,
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.Xr rc.shutdown 8 ,
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.Xr reboot 8 ,
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.Xr shutdown 8
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.Sh HISTORY
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An
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.Nm
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command appeared in
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.At v1 .
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