Command Section
REBOOT(2)                 FreeBSD System Calls Manual                REBOOT(2)

     reboot - reboot system or halt processor

     Standard C Library (libc, -lc)

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

     reboot(int howto);

     The reboot() system call 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.

     The howto argument 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.

     RB_AUTOBOOT   The default, causing the system to reboot in its usual

     RB_ASKNAME    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)kernel'', where xx is the default disk name,
                   without prompting for the file name.

     RB_DFLTROOT   Use the compiled in root device.  Normally, the system uses
                   the device from which it was booted as the root device if
                   possible.  (The default behavior is dependent on the
                   ability of the bootstrap program to determine the drive
                   from which it was loaded, which is not possible on all

     RB_DUMP       Dump kernel memory before rebooting; see savecore(8) for
                   more information.

     RB_HALT       The processor is simply halted; no reboot takes place.
                   This option should be used with caution.

     RB_POWEROFF   After halting, the shutdown code will do what it can to
                   turn off the power.  This requires hardware support.

     RB_INITNAME   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        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() system call.  See ddb(4) for more information.

     RB_NOSYNC     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_REROOT     Instead of rebooting, unmount all filesystems except the
                   one containing currently-running executable, and mount root
                   filesystem using the same mechanism which is used during
                   normal boot, based on vfs.root.mountfrom kenv(1) variable.

     RB_RDONLY     Initially mount the root file system read-only.  This is
                   currently the default, and this option has been deprecated.

     RB_SINGLE     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

     When no options are given (i.e., RB_AUTOBOOT is used), the system is
     rebooted from file ``kernel'' 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)).

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

     [EPERM]            The caller is not the super-user.

     crash(8), halt(8), init(8), reboot(8), savecore(8)

     The reboot() system call appeared in 4.0BSD.

FreeBSD 11.1-RELEASE-p4       September 18, 2015       FreeBSD 11.1-RELEASE-p4
Command Section