1.\" Copyright (c) 1980, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.man% 5.\" 6.\" @(#)reboot.2 8.1 (Berkeley) 06/04/93 7.\" 8.Dd 9.Dt REBOOT 2 10.Os BSD 4 11.Sh NAME 12.Nm reboot 13.Nd reboot system or halt processor 14.Sh SYNOPSIS 15.Fd #include <unistd.h> 16.Fd #include <sys/reboot.h> 17.Ft int 18.Fn reboot "int howto" 19.Sh DESCRIPTION 20.Fn Reboot 21reboots the system. 22Only the super-user may reboot a machine on demand. 23However, a reboot is invoked 24automatically in the event of unrecoverable system failures. 25.Pp 26.Fa Howto 27is a mask of options; the system call interface allows the following 28options, defined in the include file 29.Aq Pa sys/reboot.h , 30to be passed 31to the new kernel or the new bootstrap and init programs. 32.Bl -tag -width RB_INITNAMEA 33.It Dv RB_AUTOBOOT 34The default, causing the system to reboot in its usual fashion. 35.It Dv RB_ASKNAME 36Interpreted by the bootstrap program itself, causing it to 37prompt on the console as to what file should be booted. 38Normally, the system is booted from the file 39.Dq Em xx Ns No (0,0)vmunix , 40where 41.Em xx 42is the default disk name, 43without prompting for the file name. 44.It Dv RB_DFLTROOT 45Use the compiled in root device. 46Normally, the system uses the device from which it was booted 47as the root device if possible. 48(The default behavior is dependent on the ability of the bootstrap program 49to determine the drive from which it was loaded, which is not possible 50on all systems.) 51.It Dv RB_DUMP 52Dump kernel memory before rebooting; see 53.Xr savecore 8 54for more information. 55.It Dv RB_HALT 56the processor is simply halted; no reboot takes place. 57This option should be used with caution. 58.It Dv RB_INITNAME 59An option allowing the specification of an init program (see 60.Xr init 8 ) 61other than 62.Pa /sbin/init 63to be run when the system reboots. 64This switch is not currently available. 65.It Dv RB_KDB 66Load the symbol table and enable a built-in debugger in the system. 67This option will have no useful function if the kernel is not configured 68for debugging. 69Several other options have different meaning if combined 70with this option, although their use may not be possible 71via the 72.Fn reboot 73call. 74See 75.Xr kadb 4 76for more information. 77.It Dv RB_NOSYNC 78Normally, the disks are sync'd (see 79.Xr sync 8 ) 80before the processor is halted or rebooted. 81This option may be useful if file system changes have been made manually 82or if the processor is on fire. 83.It Dv RB_RDONLY 84Initially mount the root file system read-only. 85This is currently the default, and this option has been deprecated. 86.It Dv RB_SINGLE 87Normally, the reboot procedure involves an automatic disk consistency 88check and then multi-user operations. 89.Dv RB_SINGLE 90prevents this, booting the system with a single-user shell 91on the console. 92.Dv RB_SINGLE 93is actually interpreted by the 94.Xr init 8 95program in the newly booted system. 96.Pp 97When no options are given (i.e., 98.Dv RB_AUTOBOOT 99is used), the system is 100rebooted from file ``vmunix'' in the root file system of unit 0 101of a disk chosen in a processor specific way. 102An automatic consistency check of the disks is normally performed 103(see 104.Xr fsck 8 ) . 105.El 106.Sh RETURN VALUES 107If successful, this call never returns. 108Otherwise, a -1 is returned and an error is returned in the global 109variable 110.Va errno . 111.Sh ERRORS 112.Bl -tag -width Er 113.It Bq Er EPERM 114The caller is not the super-user. 115.El 116.Sh SEE ALSO 117.Xr kadb 4 , 118.Xr crash 8 , 119.Xr halt 8 , 120.Xr init 8 , 121.Xr reboot 8 , 122.Xr savecore 8 123.Sh BUGS 124The HP300 implementation supports neither 125.Dv RB_DFLTROOT 126nor 127.Dv RB_KDB . 128.Sh HISTORY 129The 130.Nm 131function call appeared in 132.Bx 4.0 . 133