FreeBSD nextboot (alternate kernel and boot flags)

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FreeBSD nextboot (alternate kernel and boot flags)

Postby lik » Tue Feb 09, 2010 8:40 am

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


nextboot [-f] [-o options] -k kernel
nextboot -D


The nextboot utility allows specifying an alternate kernel and/or boot
flags 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.

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

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


To boot the GENERIC kernel with the nextboot command:
Code: Select all
nextboot -k GENERIC

To enable into single user mode with the normal kernel:
Code: Select all
nextboot -o "-s" -k kernel

To remove an existing nextboot configuration:
Code: Select all
nextboot -D


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.
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Joined: Wed Dec 15, 2010 3:21 am

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