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This document provides information about the NanoBSD tools, which can be used to create FreeBSD system images for embedded applications, suitable for use on a USB key, memory card or other mass storage media.
NanoBSD is a tool developed by {phk} and now maintained by {imp}. It creates a FreeBSD system image for embedded applications, suitable for use on a USB key, memory card or other mass storage media.
The features of NanoBSD include:
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.
Everything is read-only at run-time - It is safe to pull the power-plug. There is no necessity to run man:fsck[8] after a non-graceful shutdown of the system.
Once the image is present on the medium, it is possible to boot NanoBSD. The mass storage medium is divided into three parts by default:
Two image partitions: `code#1` and `code#2`.
The [.filename]#/etc# and [.filename]#/var# directories are man:md[4] (malloc) disks.
The configuration file partition persists under the [.filename]#/cfg# directory. It contains files for [.filename]#/etc# directory and is briefly mounted read-only right after the system boot, therefore it is required to copy modified files from [.filename]#/etc# back to the [.filename]#/cfg# directory if changes are expected to persist after the system restarts.
Making Persistent Changes to [.filename]#/etc/resolv.conf#
# vi /etc/resolv.conf
# mount /cfg
# cp /etc/resolv.conf /cfg
# umount /cfg
A NanoBSD image is built using a simple [.filename]#nanobsd.sh# shell script, which can be found in the [.filename]#/usr/src/tools/tools/nanobsd# directory. This script creates an image, which can be copied on the storage medium using the man:dd[1] utility.
The necessary commands to build a NanoBSD image are:
# cd /usr/src/tools/tools/nanobsd <.>
# sh nanobsd.sh <.>
# cd /usr/obj/nanobsd.full <.>
# dd if=_.disk.full of=/dev/da0 bs=64k <.>
<.> Change the current directory to the base directory of the NanoBSD build script.
<.> Install NanoBSD onto the storage medium.
Options When Building a NanoBSD Image
When building a NanoBSD image, several build options can be passed to [.filename]#nanobsd.sh# on the command line. These options can have a significant impact on the build process.