NAME

reboot — reboot system or halt processor

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <unistd.h>
#include <sys/reboot.h>

int
reboot(int howto, char *bootstr);

DESCRIPTION

reboot() reboots the system. Only the super-user may reboot a machine on demand. However, a reboot is invoked automatically in the event of unrecoverable system failures.

howto is a mask of options; the system call interface allows the following options, defined in the include file <sys/reboot.h>, to be passed to the new kernel or the new bootstrap and init programs. In addition to the options described below, other options described in boothowto(9) may be set, but such options may be ignored by the system.

Options can be combined together by OR'ing them, eg. RB_DUMP | RB_NOSYNC would be interpreted as “dump kernel memory before rebooting and don't sync the disks”.

RB_AUTOBOOT	0x0000	The default, causing the system to reboot in its usual fashion.
RB_ASKNAME	0x0001	Interpreted by the bootstrap program itself, causing it to prompt on the console as to what file should be booted. Normally, the system is booted from the file “xx(0,0)netbsd”, where xx is the default disk name, without prompting for the file name.
RB_DUMP	0x0100	Dump kernel memory before rebooting; see savecore(8) for more information.
RB_HALT	0x0008	the processor is simply halted; no reboot takes place. This option should be used with caution.
RB_POWERDOWN	0x0808	This option is always used in conjunction with RB_HALT, and if the system hardware supports the function, the system will be powered off, otherwise it has no effect.
RB_INITNAME	0x0010	An option allowing the specification of an init program (see init(8)) other than /sbin/init to be run when the system reboots. This switch is not currently available.
RB_KDB	0x0040	Load the symbol table and enable a built-in debugger in the system. This option will have no useful function if the kernel is not configured for debugging. Several other options have different meaning if combined with this option, although their use may not be possible via the reboot() call. See ddb(4) for more information.
RB_NOSYNC	0x0004	Normally, the disks are sync'd (see sync(8)) before the processor is halted or rebooted. This option may be useful if file system changes have been made manually or if the processor is on fire.
RB_RDONLY	0x0080	Initially mount the root file system read-only. This is currently the default, and this option has been deprecated.
RB_SINGLE	0x0002	Normally, the reboot procedure involves an automatic disk consistency check and then multi-user operations. RB_SINGLE prevents this, booting the system with a single-user shell on the console. RB_SINGLE is actually interpreted by the init(8) program in the newly booted system. When no options are given (i.e., RB_AUTOBOOT is used), the system is rebooted from file ``netbsd'' in the root file system of unit 0 of a disk chosen in a processor specific way. An automatic consistency check of the disks is normally performed (see fsck(8)).
RB_STRING	0x0400	bootstr is a string passed to the firmware on the machine, if possible, if this option is set. Currently this is only implemented on the sparc and the sun3 ports.
RB_USERCONF	0x1000	Initially invoke the userconf(4) facility when the system starts up again, if it has been compiled into the kernel that is loaded.

RETURN VALUES

If successful, this call never returns. Otherwise, a -1 is returned and an error is returned in the global variable errno.

ERRORS

[EPERM]

The caller is not the super-user.

SEE ALSO

ddb(4), crash(8), halt(8), init(8), reboot(8), savecore(8), boothowto(9)

HISTORY

The reboot() function call appeared in 4.0BSD.

The RB_DFLTROOT option is now obsolete.