plucky (2) reboot.2freebsd.gz

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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);

DESCRIPTION

     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 fashion.

     RB_ASKNAME     Normally the system only prompts the user if the loader specified root file system has an
                    error.  This flag forces it to always prompt the user for the root partition.

     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 systems.)

     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_POWERCYCLE  After halting, the shutdown code will do what it can to turn off the power and then turn the
                    power back on.  This requires hardware support, usually an auxiliary microprocessor that can
                    sequence the power supply.  At present only the ipmi(4) driver implements this feature.

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

     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
                    system.

     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)).

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

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

HISTORY

     The reboot() system call appeared in 4.0BSD.