1.\" Copyright (c) 1990, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 4. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)reboot.8 8.1 (Berkeley) 6/9/93 29.\" $FreeBSD$ 30.\" 31.Dd Dec 12, 2015 32.Dt REBOOT 8 33.Os 34.Sh NAME 35.Nm reboot , 36.Nm halt , 37.Nm fastboot , 38.Nm fasthalt 39.Nd stopping and restarting the system 40.Sh SYNOPSIS 41.Nm halt 42.Op Fl lNnpq 43.Op Fl k Ar kernel 44.Nm 45.Op Fl dlNnpqr 46.Op Fl k Ar kernel 47.Nm fasthalt 48.Op Fl lNnpq 49.Op Fl k Ar kernel 50.Nm fastboot 51.Op Fl dlNnpq 52.Op Fl k Ar kernel 53.Sh DESCRIPTION 54The 55.Nm halt 56and 57.Nm 58utilities flush the file system cache to disk, send all running processes 59a 60.Dv SIGTERM 61(and subsequently a 62.Dv SIGKILL ) 63and, respectively, halt or restart the system. 64The action is logged, including entering a shutdown record into the user 65accounting database. 66.Pp 67The options are as follows: 68.Bl -tag -width indent 69.It Fl d 70The system is requested to create a crash dump. 71This option is 72supported only when rebooting, and it has no effect unless a dump 73device has previously been specified with 74.Xr dumpon 8 . 75.It Fl k Ar kernel 76Boot the specified 77.Ar kernel 78on the next system boot. 79If the kernel boots successfully, the 80.Em default 81kernel will be booted on successive boots, this is a one-shot option. 82If the boot fails, the system will continue attempting to boot 83.Ar kernel 84until the boot process is interrupted and a valid kernel booted. 85This may change in the future. 86.It Fl l 87The halt or reboot is 88.Em not 89logged to the system log. 90This option is intended for applications such as 91.Xr shutdown 8 , 92that call 93.Nm 94or 95.Nm halt 96and log this themselves. 97.It Fl N 98The file system cache is not flushed during the initial process clean-up, 99however the kernel level 100.Xr reboot 2 101is still processed with a sync. 102This option can be useful for performing a 103.Dq best-effort 104reboot when devices might be unavailable. 105This can happen when devices have been disconnected, such as with 106.Xr iscsi 4 . 107.It Fl n 108The file system cache is not flushed. 109This option should probably not be used. 110.It Fl p 111The system will turn off the power if it can. 112If the power down action fails, the system 113will halt or reboot normally, depending on whether 114.Nm halt 115or 116.Nm 117was called. 118.It Fl q 119The system is halted or restarted quickly and ungracefully, and only 120the flushing of the file system cache is performed (if the 121.Fl n 122option is not specified). 123This option should probably not be used. 124.It Fl r 125The system kills all processes, unmounts all filesystems, mounts the new 126root filesystem, and begins the usual startup sequence. 127After changing vfs.root.mountfrom with 128.Xr kenv 8 , 129.Nm Fl r 130can be used to change the root filesystem while preserving kernel state. 131.El 132.Pp 133The 134.Nm fasthalt 135and 136.Nm fastboot 137utilities are nothing more than aliases for the 138.Nm halt 139and 140.Nm 141utilities. 142.Pp 143Normally, the 144.Xr shutdown 8 145utility is used when the system needs to be halted or restarted, giving 146users advance warning of their impending doom and cleanly terminating 147specific programs. 148.Sh EXAMPLES 149Replace current root filesystem with UFS mounted from 150.Pa /dev/ada0s1a : 151.Bd -literal -offset indent 152kenv vfs.root.mountfrom=ufs:/dev/ada0s1a 153reboot -r 154.Ed 155.Sh SEE ALSO 156.Xr getutxent 3 , 157.Xr boot 8 , 158.Xr dumpon 8 , 159.Xr nextboot 8 , 160.Xr savecore 8 , 161.Xr shutdown 8 , 162.Xr sync 8 163.Sh HISTORY 164A 165.Nm 166utility appeared in 167.At v6 . 168