1.\" $NetBSD: reboot.8,v 1.27 2010/12/12 11:38:42 pooka Exp $ 2.\" 3.\" Copyright (c) 1990, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)reboot.8 8.1 (Berkeley) 6/9/93 31.\" 32.Dd October 21, 2008 33.Dt REBOOT 8 34.Os 35.Sh NAME 36.Nm reboot , 37.Nm poweroff , 38.Nm halt 39.Nd restarting, powering down and stopping the system 40.Sh SYNOPSIS 41.Nm halt 42.Op Fl dlnpq 43.Nm poweroff 44.Op Fl dlnq 45.Nm 46.Op Fl dlnq 47.Op Ar arg ... 48.Sh DESCRIPTION 49The 50.Nm poweroff , 51.Nm halt 52and 53.Nm 54utilities flush the file system cache to disk, send all running processes 55a 56.Dv SIGTERM , 57wait for up to 30 seconds for them to die, send a 58.Dv SIGKILL 59to the survivors and, respectively, power down, halt or restart the system. 60The action is logged, including entering a shutdown record into the login 61accounting file and sending a message via 62.Xr syslog 3 . 63.Pp 64The options are as follows: 65.Bl -tag -width Ds 66.It Fl d 67Create a dump before halting or restarting. 68This option is useful for debugging system dump procedures or 69capturing the state of a corrupted or misbehaving system. 70.It Fl l 71Suppress sending a message via 72.Xr syslog 3 73before halting or restarting. 74.It Fl n 75Do not flush the file system cache. 76This option should be used with extreme caution. 77It can be used if a disk or a processor is on fire. 78.It Fl p 79Attempt to powerdown the system. 80If the powerdown fails, or the system does not support 81software powerdown, the system will halt. 82This option is only valid for 83.Nm halt . 84.It Fl q 85Do not give processes a chance to shut down before halting or restarting. 86This option should not normally be used. 87.El 88.Pp 89If there are any arguments passed to 90.Nm reboot 91they are concatenated with spaces and passed as 92.Fa bootstr 93to the 94.Xr reboot 2 95system call. 96The string is passed to the firmware on platforms that support it. 97.Pp 98Normally, the 99.Xr shutdown 8 100utility is used when the system needs to be halted or restarted, giving 101users advance warning of their impending doom. 102.Sh SEE ALSO 103.Xr reboot 2 , 104.Xr syslog 3 , 105.Xr utmp 5 , 106.Xr boot 8 , 107.Xr init 8 , 108.Xr rescue 8 , 109.Xr shutdown 8 , 110.Xr sync 8 111.Sh HISTORY 112A 113.Nm 114command appeared in 115.At v6 . 116.Pp 117The 118.Nm poweroff 119command first appeared in 120.Nx 1.5 . 121.Sh CAVEATS 122Once the command has begun its work, stopping it before it completes 123will probably result in a system so crippled it must be 124physically reset. 125To prevent premature termination, the command 126blocks many signals early in its execution. 127However, nothing can defend against deliberate attempts to evade this. 128.Pp 129This command will stop the system without running any 130.Xr shutdown 8 131scripts. 132Amongst other things, this means that swapping will not be 133disabled so that 134.Xr raid 4 135can shutdown cleanly. 136You should normally use 137.Xr shutdown 8 138unless you are running in single user mode. 139.Sh BUGS 140The single user shell will ignore the 141.Dv SIGTERM 142signal. 143To avoid waiting for the timeout when 144rebooting or halting from the single user shell, you have to 145.Ic exec reboot 146or 147.Ic exec halt . 148