NEWBTCONF(8) BSD System Manager's Manual NEWBTCONF(8)
newbtconf -- multiple boot-up configurations
newbtconf new-conf-name [orig-conf-name]
newbtconf is used to set up the system in such a way that the user is
offered a selection of environments in which to boot the system up into.
The most obvious application being for laptops to provide a network and
non-network environment after a successful boot into multi-user mode.
In order to accomplish this task, the files usually associated with
establishing the current system's running configuration are replaced with
symbolic links which are adjusted with each boot to point to the appro-
priate file for the desired run-time environment. This is accomplished
by directing all of the symbolic links through a directory which itself
is a symbolic link (/etc/etc.current), to the destination files. At each
bootup, the selection made changes which directory /etc/etc.current
Through doing this and reloading /etc/rc.conf in /etc/rc after the link
has been established, the resulting run-time configuration is effectively
controlled without the need to directly edit any files. The default
boot-up environment is selected by manually directing which configuration
directory /etc/etc.default points to. As opposed to /etc/etc.current
(which is updated with every boot), /etc/etc.default is not automatically
By default, NetBSD only has one boot-up configuration - that set in the
file /etc/rc.conf. In order to initialize the system for operating in a
manner which supports multiple boot configurations, newbtconf must be run
with an argument of 'init'. This will create two symbolic links
/etc/etc.current and /etc/etc.default to the directory /etc/etc.network.
The following files are all moved into that directory and symbolic links
put in their place, in /etc, pointing to /etc/etc.current/<filename>:
To test that this has been performed correctly, reboot your system into
NetBSD. After the kernel has autoconfigured and tty flags have been set,
a prompt should appear, preceded by the following like, looking like
Which configuration [network] ?
The 's are used to indicate the default configuration, which can be
selected by just pressing return. If there were other configurations
available at this stage, you would have 30 seconds to enter that name and
Once an initial configuration has been set up, we can proceed to set up
further run time environments. This is done by invoking newbtconf with
the name of the new configuration to be created. By default, this step
will use the current configuration files as the basis for this setup
unless a second parameter is given - that of the configuration to use as
the basis for the new one. Upon completion, a new directory,
/etc/etc.<newname>, will have been created, priming the directory with
the appropriate files for editing. For example, if we do newbtconf nonet
network it would create a directory named /etc/etc.nonet and copy all the
files from /etc/etc.network into that directory. Upon rebooting, we
Which configuration [network] ?
To set up the system for booting into the ``nonet'' configuration, the
files in /etc/etc.nonet need be edited.
If you wanted to make ``nonet'' the default configuration when booting,
you would need delete the symbolic link /etc/etc.default and create a new
symbolic link (with the same name) to /etc/etc.nonet. Booting up after
having made such a change would result in the following being displayed:
Which configuration [nonet] ?
Assuming that we performed the above command successfully, in order to
successfully configure NetBSD to not configure interfaces (or generate no
errors from attempting to do so), the following settings (at least)
should be used in /etc/etc.nonet/rc.conf:
Of course other networking services, such as NTP, routed, etc, are all
expected to be ``NO''. In general, the only setting that should be
``YES'' is syslogd, and perhaps cron (if your cron scripts don't need the
network) or screenblank/wscons (if applicable). Other actions such as
deleting any NFS mounts from /etc/etc.nonet/fstab would also need to be
Reverting multiple boot configurations
Multiple boot configurations can be deactivated by running newbtconf with
an argument of revert. All the symlinks mentioned above are then removed
and the files they point to are copied to their default place. This
effectively makes the currently selected configuration the only one
active. The symbolic links /etc/etc.current and /etc/etc.default are
also removed so upon rebooting no configuration selection menu is dis-
played. Note that the previously created configurations (in
/etc/etc.<name>) are not removed.
/etc/etc.current Symbolic link to current config directory.
/etc/etc.default Symbolic link to default config directory.
/etc/defaultdomain These files all become symbolic links.
The newbtconf program first appeared in NetBSD 1.5.
This shell script was written by Darren Reed <darrenrATNetBSD.org> with
initial input from
Matthew Green <mrgATNetBSD.org> on how to approach this problem.
It presently does not display a count down timer whilst waiting for input
to select which configuration and nor does it abort said timer when a key
is first pressed.
The management of the overall collection of multiple configurations is
much more manual than it ought to be. A general system configuration
tool needs to be written to ease their management.
BSD January 6, 2003 BSD