1.\" $NetBSD: reboot.8,v 1.23 2007/06/03 22:39:47 uwe 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 June 3, 2007 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 SIGTERM, wait for several seconds for them to die, send a SIGKILL to the 56survivors and, respectively, power down, halt or restart the system. 57The action is logged, including entering a shutdown record into the login 58accounting file and sending a message via 59.Xr syslog 3 . 60.Pp 61The options are as follows: 62.Bl -tag -width Ds 63.It Fl d 64Create a dump before halting or restarting. 65This option is useful for debugging system dump procedures or 66capturing the state of a corrupted or misbehaving system. 67.It Fl l 68Suppress sending a message via 69.Xr syslog 3 70before halting or restarting. 71.It Fl n 72Do not flush the file system cache. 73This option should be used with extreme caution. 74It can be used if a disk or the processor is on fire. 75.It Fl p 76Attempt to powerdown the system. 77If the powerdown fails, or the system does not support 78software powerdown, the system will halt. 79This option is only valid for 80.Nm halt . 81.It Fl q 82Do not give processes a chance to shut down before halting or restarting. 83This option should not normally be used. 84.El 85.Pp 86If there are any arguments passed to 87.Nm reboot 88they are concatenated with spaces and passed as 89.Fa bootstr 90to 91.Xr reboot 2 92system call. 93The string is passed to the firmware on platforms that support it. 94.Pp 95Normally, the 96.Xr shutdown 8 97utility is used when the system needs to be halted or restarted, giving 98users advance warning of their impending doom. 99.Sh SEE ALSO 100.Xr reboot 2 , 101.Xr syslog 3 , 102.Xr utmp 5 , 103.Xr boot 8 , 104.Xr shutdown 8 , 105.Xr sync 8 106.Sh HISTORY 107A 108.Nm 109command appeared in 110.At v6 . 111.Pp 112The 113.Nm poweroff 114command first appeared in 115.Nx 1.5 . 116.Sh CAVEATS 117Once the command has begun its work, stopping it before it completes 118will probably result in a system so crippled it must be 119physically reset. 120To prevent premature termination, the command 121blocks many signals early in its execution. 122However, nothing can defend against deliberate attempts to evade this. 123.Pp 124This command will stop the system without running any 125.Xr shutdown 8 126scripts. Amongst other things, this means that swapping will not be 127disabled so that 128.Xr raid 4 129can shutdown cleanly. You should normally use 130.Xr shutdown 8 131unless you are running in single user mode. 132.Sh BUGS 133The single user shell will ignore the SIGTERM signal. 134To avoid waiting for the timeout when 135rebooting or halting from the single user shell, you have to 136.Ic exec reboot 137or 138.Ic exec halt . 139