1.\" $OpenBSD: reboot.2,v 1.8 2000/10/18 05:12:11 aaron Exp $ 2.\" $NetBSD: reboot.2,v 1.5 1995/02/27 12:36:02 cgd Exp $ 3.\" 4.\" Copyright (c) 1980, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)reboot.2 8.1 (Berkeley) 6/4/93 36.\" 37.Dd June 4, 1993 38.Dt REBOOT 2 39.Os 40.Sh NAME 41.Nm reboot 42.Nd reboot system or halt processor 43.Sh SYNOPSIS 44.Fd #include <unistd.h> 45.Fd #include <sys/reboot.h> 46.Ft int 47.Fn reboot "int howto" 48.Sh DESCRIPTION 49.Fn reboot 50reboots the system. 51Only the superuser may reboot a machine on demand. 52However, a reboot is invoked 53automatically in the event of unrecoverable system failures. 54.Pp 55.Fa howto 56is a mask of options; the system call interface allows the following 57options, defined in the include file 58.Aq Pa sys/reboot.h , 59to be passed 60to the new kernel or the new bootstrap and init programs. 61.Bl -tag -width RB_INITNAMEA 62.It Dv RB_AUTOBOOT 63The default, causing the system to reboot in its usual fashion. 64.It Dv RB_ASKNAME 65Interpreted by the bootstrap program itself, causing it to 66prompt on the console as to what file should be booted. 67Normally, the system is booted from the file 68.Dq Em xx Ns No (0,0)bsd , 69where 70.Em xx 71is the default disk name, 72without prompting for the file name. 73.It Dv RB_DFLTROOT 74Use the compiled in root device. 75Normally, the system uses the device from which it was booted 76as the root device if possible. 77(The default behavior is dependent on the ability of the bootstrap program 78to determine the drive from which it was loaded, which is not possible 79on all systems.) 80.It Dv RB_DUMP 81Dump kernel memory before rebooting; see 82.Xr savecore 8 83for more information. 84.It Dv RB_HALT 85the processor is simply halted; no reboot takes place. 86.It Dv RB_POWERDOWN 87If used in conjunction with 88.Dv RB_HALT , 89and if the system hardware supports the function, the system will be 90powered off. 91.It Dv RB_INITNAME 92An option allowing the specification of an init program (see 93.Xr init 8 ) 94other than 95.Pa /sbin/init 96to be run when the system reboots. 97This switch is not currently available. 98.It Dv RB_KDB 99Load the symbol table and enable a built-in debugger in the system. 100This option will have no useful function if the kernel is not configured 101for debugging. 102Several other options have different meaning if combined 103with this option, although their use may not be possible via the 104.Fn reboot 105call. 106See 107.Xr kadb 4 108for more information. 109.It Dv RB_NOSYNC 110Normally, the disks are sync'd (see 111.Xr sync 8 ) 112before the processor is halted or rebooted. 113This option may be useful if file system changes have been made manually 114or if the processor is on fire. 115.It Dv RB_RDONLY 116Initially mount the root file system read-only. 117This is currently the default, and this option has been deprecated. 118.It Dv RB_SINGLE 119Normally, the reboot procedure involves an automatic disk consistency 120check and then multi-user operations. 121.Dv RB_SINGLE 122prevents this, booting the system with a single-user shell 123on the console. 124.Dv RB_SINGLE 125is actually interpreted by the 126.Xr init 8 127program in the newly booted system. 128.Pp 129When no options are given (i.e., 130.Dv RB_AUTOBOOT 131is used), the system is 132rebooted from file ``bsd'' in the root file system of unit 0 133of a disk chosen in a processor specific way. 134An automatic consistency check of the disks is normally performed 135(see 136.Xr fsck 8 ) . 137.El 138.Sh RETURN VALUES 139If successful, this call never returns. 140Otherwise, a \-1 is returned and an error is returned in the global 141variable 142.Va errno . 143.Sh ERRORS 144.Bl -tag -width Er 145.It Bq Er EPERM 146The caller is not the superuser. 147.El 148.Sh SEE ALSO 149.Xr kadb 4 , 150.Xr crash 8 , 151.Xr halt 8 , 152.Xr init 8 , 153.Xr reboot 8 , 154.Xr savecore 8 155.Sh HISTORY 156The 157.Fn reboot 158function call appeared in 159.Bx 4.0 . 160.Sh BUGS 161Not all platforms support all possible arguments. 162For example, 163.Dv RB_POWERDOWN 164is supported only on the i386, sparc, and mac68k platforms. 165