autoboot(ADM)                   19 June 1992                   autoboot(ADM)


 Name

    autoboot - automatically boot the system

 Description

    The system can be set up to go through the boot stages automatically (as
    defined in /etc/default/boot) when the computer is turned on (booted),
    provided no key is pressed at the boot(HW) prompt.

    If boot times out and AUTOBOOT=YES, then the word ``auto'' is passed in
    the boot string and init(M) is passed a -a flag.

    In addition, the TIMEOUT entry can be set to specify the number of
    seconds to wait before timing out.

    The autoboot procedure checks the file /etc/default/boot for the follow-
    ing instructions on autobooting:

    AUTOBOOT=YES or NO         Whether or not boot(HW) times out and loads
                               the kernel.  boot looks for this variable in
                               the /etc/default/boot file on its default de-
                               vice.

    MULTIUSER=YES or NO        Whether or not init(M) invokes sulogin or
                               proceeds to multi-user mode.

    PANICBOOT=YES or NO        Whether or not the system reboots after a
                               panic().  This variable is read from
                               /etc/default/boot by init.

    RONLYROOT=YES or NO        Whether or not the root filesystem is mounted
                               readonly.  This must be used only during in-
                               stallation, and not for a normal boot. It will
                               effectively prevent writing to the filesystem.

    DEFBOOTSTR=bootstring      Set default bootstring to bootstring.  This is
                               the string used by boot when the user presses
                               <Return> only to the ``Boot:''  prompt, or
                               when boot times out.

    SYSTTY=x                   If x is 1, the system console device is set to
                               the serial adapter at COM. If x is 0, the sys-
                               tem console is set to the main display
                               adapter.

    SLEEPTIME=n                Sets the time (in seconds) between calls to
                               sync.

    TIMEOUT=n                  Where n is the number of seconds to timeout at
                               the ``Boot:''  prompt before booting the ker-
                               nel (if AUTOBOOT=YES).  If TIMEOUT is unspeci-
                               fied, defaults to one minute.

    If either the /etc/default/boot file or the variable needed cannot be
    found, the variable is assumed to be NO.  However, if the filesystem can-
    not be found, PANICBOOT is set to YES.

    If the UNIX mail system, mail(C), is installed on the system, the output
    of the boot sequence is mailed to root.  Otherwise, the system adminis-
    trator should check the file /etc/bootlog for the boot sequence output.
    The output of fsck(ADM) is temporarily saved in the file /dev/recover
    before it is moved to /etc/bootlog and finally may be sent to the system
    administrator via mail.

    Other boot options which take affect during autoboot are documented on
    the boot(HW) manual page.

 Files

    /etc/bootlog        boot output log for autobooting systems
    /etc/default/boot   boot information file
    /etc/rc2            instructions for entering multi-user mode, includes
                        mounting and checking additional filesystems
    /etc/sulogin        executed at startup, prompts the user to press
                        <Ctrl>d for multi-user mode or to enter the root
                        password for maintenance mode
    /dev/recover        allows saving of fsck output
    /dev/scratch        temporary fsck file for large filesystems

 See also

    boot(HW), fsck(ADM), init(M)

 Notes

    The utilities invoked during the boot procedure are passed the -a flag
    and time out only when the system autoboots.  For example, asktime(ADM)
    times out after 30 seconds when the system autoboots, but waits for a
    response from the user any other time it is invoked.

    The previous boot modes of AUTO=CLEAN, DIRTY, NEVER have been retained
    for backwards compatibility, but are ignored if any of the newer modes
    are present.

 Value added

    autoboot is an extension to AT&T System V developed by The Santa Cruz
    Operation, Inc.