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.\" 3. 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 December 20, 2017 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 cdlNnpqr 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 c 70The system will turn off the power and then turn it back on if it can. 71If the power down action fails, the system 72will halt or reboot normally, depending on whether 73.Nm halt 74or 75.Nm 76was called. 77At the present time, only the 78.Xr ipmi 4 79driver implements the power cycle functionality and only on hardware 80with a BMC that supports power cycling. 81Unlike power off, the amount of hardware that supports power cycling 82is small. 83.It Fl d 84The system is requested to create a crash dump. 85This option is 86supported only when rebooting, and it has no effect unless a dump 87device has previously been specified with 88.Xr dumpon 8 . 89.It Fl k Ar kernel 90Boot the specified 91.Ar kernel 92on the next system boot. 93If the kernel boots successfully, the 94.Em default 95kernel will be booted on successive boots, this is a one-shot option. 96If the boot fails, the system will continue attempting to boot 97.Ar kernel 98until the boot process is interrupted and a valid kernel booted. 99This may change in the future. 100.It Fl l 101The halt or reboot is 102.Em not 103logged to the system log. 104This option is intended for applications such as 105.Xr shutdown 8 , 106that call 107.Nm 108or 109.Nm halt 110and log this themselves. 111.It Fl N 112The file system cache is not flushed during the initial process clean-up, 113however the kernel level 114.Xr reboot 2 115is still processed with a sync. 116This option can be useful for performing a 117.Dq best-effort 118reboot when devices might be unavailable. 119This can happen when devices have been disconnected, such as with 120.Xr iscsi 4 . 121.It Fl n 122The file system cache is not flushed. 123This option should probably not be used. 124.It Fl p 125The system will turn off the power if it can. 126If the power down action fails, the system 127will halt or reboot normally, depending on whether 128.Nm halt 129or 130.Nm 131was called. 132.It Fl q 133The system is halted or restarted quickly and ungracefully, and only 134the flushing of the file system cache is performed (if the 135.Fl n 136option is not specified). 137This option should probably not be used. 138.It Fl r 139The system kills all processes, unmounts all filesystems, mounts the new 140root filesystem, and begins the usual startup sequence. 141After changing vfs.root.mountfrom with 142.Xr kenv 1 , 143.Nm Fl r 144can be used to change the root filesystem while preserving kernel state. 145This requires the 146.Xr tmpfs 5 147kernel module to be loaded because 148.Xr init 8 149needs a place to store itself after the old root is unmounted, but 150before the new root is in place. 151.El 152.Pp 153The 154.Nm fasthalt 155and 156.Nm fastboot 157utilities are nothing more than aliases for the 158.Nm halt 159and 160.Nm 161utilities. 162.Pp 163Normally, the 164.Xr shutdown 8 165utility is used when the system needs to be halted or restarted, giving 166users advance warning of their impending doom and cleanly terminating 167specific programs. 168.Sh EXAMPLES 169Replace current root filesystem with UFS mounted from 170.Pa /dev/ada0s1a : 171.Bd -literal -offset indent 172kenv vfs.root.mountfrom=ufs:/dev/ada0s1a 173reboot -r 174.Ed 175.Pp 176This mechanism can also be used with NFS, with a caveat that 177it only works with NFSv4, and requires a numeric IPv4 address: 178.Bd -literal -offset indent 179kenv vfs.root.mountfrom=nfs:192.168.1.1:/share/name 180reboot -r 181.Ed 182.Sh SEE ALSO 183.Xr kenv 1 , 184.Xr getutxent 3 , 185.Xr ipmi 4 , 186.Xr boot 8 , 187.Xr dumpon 8 , 188.Xr nextboot 8 , 189.Xr savecore 8 , 190.Xr shutdown 8 , 191.Xr sync 8 192.Sh HISTORY 193A 194.Nm 195utility appeared in 196.Bx 4.0 . 197