freebsd man page for nextboot

NEXTBOOT(8)						    BSD System Manager's Manual 					       NEXTBOOT(8)

NAME
     nextboot -- specify an alternate kernel and boot flags for the next reboot

SYNOPSIS
     nextboot [-e variable=value] [-f] [-k kernel] [-o options]
     nextboot -D

DESCRIPTION
     The nextboot utility allows specifying some combination of an alternate kernel, boot flags and kernel environment for the next time the
     machine is booted.  Once the loader(8) loads in the new kernel information, it is deleted so in case the new kernel hangs the machine, once
     it is rebooted, the machine will automatically revert to its previous configuration.

     The options are as follows:

     -D 	 Invoking nextboot with this option removes an existing nextboot configuration.

     -e variable=value
		 This option adds the provided variable and value to the kernel environment.  The value is quoted when written to the nextboot
		 configuration.

     -f 	 This option disables the sanity checking which checks if the kernel really exists before writing the nextboot configuration.

     -k kernel	 This option specifies a kernel directory relative to /boot to load the kernel and any modules from.

     -o options  This option allows the passing of kernel flags for the next boot.

FILES
     /boot/nextboot.conf  The configuration file that the nextboot configuration is written into.

EXAMPLES
     To boot the GENERIC kernel with the nextboot command:

	   nextboot -k GENERIC

     To enable into single user mode with the normal kernel:

	   nextboot -o "-s" -k kernel

     To remove an existing nextboot configuration:

	   nextboot -D

SEE ALSO
     boot(8), loader(8)

HISTORY
     The original nextboot manual page first appeared in FreeBSD 2.2.  It used a very different interface to achieve similar results.

     The current incarnation of nextboot appeared in FreeBSD 5.0.

AUTHORS
     This manual page was written by Gordon Tetlow <gordon@FreeBSD.org>.

BUGS
     The nextboot code is implemented in the loader(8).  It is not the most thoroughly tested code.  It is also my first attempt to write in
     Forth.

     Finally, it does some evil things like writing to the file system before it has been checked.  If it scrambles your file system, do not blame
     me.

BSD
								 January 31, 2012							       BSD