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

NAME	-- utility used	to create a FreeBSD system image suitable for
     embedded applications

SYNOPSIS	[-bhkw]	[-c config-file]

     The utility is a script	which produces a minimal implementa-
     tion of FreeBSD (called NanoBSD), which typically fits on a small media
     such as a Compact Flash card, or other mass storage medium.  It can be
     used to build specialized install images, designed	for easy installation
     and maintenance.

     The following options are available:

	   -b		   Skip	the build stages (both for kernel and world).

	   -c config-file  Specify the configuration file to use.

	   -h		   Display usage information.

	   -k		   Skip	the buildkernel	stage of the build.

	   -w		   Skip	the buildworld stage of	the build.

     The features of NanoBSD include:

	   o   Ports and packages work as in FreeBSD.  Every single applica-
	       tion can	be installed and used in a NanoBSD image, the same way
	       as in FreeBSD.
	   o   No missing functionality.  If it	is possible to do something
	       with FreeBSD, it	is possible to do the same thing with NanoBSD,
	       unless the specific feature or features were explicitly removed
	       from the	NanoBSD	image when it was created.
	   o   Everything is read-only at run-time.  It	is safe	to pull	the
	       power-plug.  There is no	necessity to run fsck(8) after a non-
	       graceful	shutdown of the	system.
	   o   Easy to build and customize.  Making use	of just	one shell
	       script and one configuration file it is possible	to build re-
	       duced and customized images satisfying any arbitrary set	of re-

   NanoBSD Media Layout
     The mass storage medium is	divided	into three parts by default (which are
     normally mounted read-only):

	   o   Two image partitions: code#1 and	code#2.
	   o   The configuration file partition, which can be mounted under
	       the /cfg	directory at run time.

     The /etc and /var directories are md(4) (malloc backed) disks.

     The configuration file partition persists under the /cfg directory.  It
     contains files for	/etc directory and is briefly mounted read-only	right
     after the system boot, therefore it is required to	copy modified files
     from /etc back to the /cfg	directory if changes are expected to persist
     after the system restarts.

     A NanoBSD image is	built using a simple	shell script, which
     can be found in the src/tools/tools/nanobsd directory.  This script cre-
     ates a bootable image, which can be copied	on the storage medium using
     the dd(1) utility.

     The necessary commands to build and install a NanoBSD image are:

	   cd /usr/src/tools/tools/nanobsd
	   cd /usr/obj/nanobsd.full
	   dd if=_.disk.full of=/dev/da0 bs=64k

     This is probably the most important and most interesting feature of
     NanoBSD.  This is also where you will be spending most of the time	when
     developing	with NanoBSD.

     Customization is done in two ways:

	   o   Configuration options.
	   o   Custom functions.

     With configuration	settings, it is	possible to configure options passed
     to	both the buildworld and	installworld stages of the NanoBSD build
     process, as well as internal options passed to the	main build process of
     NanoBSD.  Through these options it	is possible to cut the system down, so
     it	will fit on as little as 64MB.	You can	use the	configuration options
     to	trim down the system even more,	until it will consist of just the ker-
     nel and two or three files	in the userland.

     The configuration file consists of	configuration options, which override
     the default values.  The most important directives	are:

	   NANO_NAME	 Build name (used to construct the working directory

	   NANO_SRC	 Path to the source tree used to build the image.

	   NANO_KERNEL	 Name of the kernel configuration file used to build
			 the kernel.

			 Controls the options passed to	boot0cfg(8); these
			 dictate boot0's behaviour.

			 The boot0 loader to use relative to the NANO_WORLDDIR
			 variable.  This defaults to boot/boot0sio and should
			 be overridden to boot/boot0 to	provide	a VGA console.

	   CONF_BUILD	 Options passed	to the buildworld stage	of the build.

	   CONF_INSTALL	 Options passed	to the installworld stage of the

	   CONF_WORLD	 Options passed	to both	the buildworld and
			 installworld stages of	the build.

	   FlashDevice	 Defines the type of media to use.  Check the
			 FlashDevice.sub file for more details.

     For more configuration options, please check the script.

     To	build NanoBSD image using the nanobsd.conf configuration file, use the
     following command:

	   sh -c nanobsd.conf

     It	is possible to fine-tune NanoBSD using shell functions in the configu-
     ration file.  The following example illustrates the basic model of	custom

	   cust_foo () (
		   echo	"bar=topless" >	\
	   customize_cmd cust_foo

     There are a few pre-defined customization functions ready for use:

	   cust_comconsole	Disables getty(8) on the virtual syscons(4)
				terminals (/dev/ttyv*) and enables the use of
				the first serial port as the system console.

	   cust_allow_ssh_root	Allow root to log in via sshd(8).

	   cust_install_files	Installs files from the	nanobsd/Files direc-
				tory, which contains some useful scripts for
				system administration.

     src/tools/tools/nanobsd  Base directory of	the NanoBSD build script.

     Making persistent changes to /etc/resolv.conf:

	   vi /etc/resolv.conf
	   mount /cfg
	   cp /etc/resolv.conf /cfg
	   umount /cfg

     A more useful example of a	customization function is the following, which
     changes the default size of the /etc directory from 5MB to	30MB:

	   cust_etc_size () (
		   cd ${NANO_WORLDDIR}/conf
		   echo	30000 >	default/etc/md_size
	   customize_cmd cust_etc_size

     make.conf(5), boot(8), boot0cfg(8), picobsd(8)

     The utility first appeared in FreeBSD 6.0.

     NanoBSD was developed by Poul-Henning Kamp	<>.  This man-
     ual page was written by Daniel Gerzo <>.

BSD				August 28, 2006				   BSD


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