BusyBox

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BusyBox

Screenshot of BusyBox
Design by	Bruce Perens
Developed by	Erik Andersen, Rob Landley, Denis Vlasenko
Latest release	1.10.2 / May 8, 2008 (2008-05-08); 36 days ago
Written in	C
OS	Linux
Genre	Independent SUSp XCU implementation
License	GNU General Public License
Website	http://www.busybox.net

BusyBox is a software application which provides many standard Unix tools, much like the larger (but more capable) GNU Core Utilities. BusyBox is designed to be a small executable for use with Linux, which makes it ideal for special purpose Linux distributions and embedded devices. It has been called "The Swiss Army Knife of Embedded Linux". It is functionally equivalent to the crunchgen^[1] command in FreeBSD, developed by James da Silva in 1994 at the University of Maryland, College Park.

Released under the GNU General Public License, version 2 [1], BusyBox is free software.

In late 2007, BusyBox also came to prominence for actively prosecuting alleged violations of its copyright under GPL in US-based courts of law.

1 History
2 Features
- 2.1 Single binary
3 Examples
4 Appliances
5 GPL lawsuits
6 Notes
7 External links

[edit] History

Originally written by Bruce Perens in 1996, the intent of BusyBox was to put a complete bootable system on a single floppy that would be both a rescue disk and an installer for the Debian distribution. It has since then become the de facto standard for embedded Linux devices and Linux distribution installers. Since each Linux executable requires several kilobytes of overhead, having the BusyBox program combine over two hundred programs together can save considerable space.

BusyBox was maintained by Enrique Zanardi and focused on the needs of the Debian boot-floppies installer system until early 1998, when it was taken over by Dave Cinege for The Linux Router Project (LRP). Cinege made several additions, created a modularized build environment, and shifted BusyBox's focus into general high level embedded systems. As LRP development slowed down in 1999, Erik Andersen, then of Lineo, Inc., took over the project and was the official maintainer between December 1999 and March 2006. During this time the Linux embedded market place exploded in growth, and BusyBox matured greatly, expanding both its user base and functionality.

Denis Vlasenko is the current maintainer of BusyBox.

[edit] Features

BusyBox can be customized to provide a subset of over two hundred utilities. It can provide most of the utilities specified in the Single Unix Specification plus many others that a user would expect to see on a Linux system. BusyBox uses the ash shell. ^[2] ^[3]

A full list of the utilities implemented can be found on the BusyBox site.^[4]

[edit] Single binary

Typical computer programs have a separate binary (executable) file for each application. BusyBox is a single binary, which is a conglomerate of many applications, each of which can be accessed by calling the single BusyBox binary with various names (supported by having a symbolic link for each different name[2]) in a specific manner with appropriate arguments.

BusyBox benefits from the single binary approach as it reduces the overheads introduced by the executable file format (typically ELF), and it allows code to be shared between multiple applications without requiring a library.

Sharing of this common code, along with routines written with size-optimization in mind, enables a BusyBox system to be much smaller than a system built with the corresponding full versions of the utilities replaced by BusyBox.

[edit] Examples

Programs included in BusyBox can be run simply by adding their name as an argument to the BusyBox executable:

/bin/busybox ls

More commonly, the desired command names are linked (using hard or symbolic links) to the BusyBox executable; BusyBox notices the name it is called as, and runs the appropriate command, for example just

/bin/ls

after /bin/ls is linked to /bin/busybox.

[edit] Appliances

It is very common to find BusyBox used in Linux-based appliances, examples of which include:

Actiontec GT701 DSL Modem/Router (GT701-WG Wireless DSL Modem/Router) bundled mostly with Qwest DSL.
Actiontec M1000 DSL Modem/Router, bundled mostly with Qwest DSL.
Actiontec MI424WR MoCA wireless router, bundled mostly with Verizon FiOS.
Amazon Kindle book reader.
ASUS wireless broadband router, Asus WL-500g, AM604G.
BT Home Hub.
Some D-Link products (e.g. the DSL-500B, DSL-504T, DSL-524T, DSL-564T, DSL-584T, DSL2500U, DSL2540U, DSL2640U, DSL-G604T, DSL-G624T, DSL-G664T and DSL-G684T routers).
Dream Multimedia's Dreambox, a hobbyist DVB receiver.
Some Edimax products (eg EW-7206APg Wifi Access Point).
Emprex ME1 HD Multimedia Enclosure.
Freebox a DSL Modem/Router distributed by Iliad, a French telecom company.
Gamepark Holdings GP2X open-source Linux game player.
HP Media Vault.
IBM Hardware Management Console (HMC).
Lacie Ethernet Big Disk 1TB. [3]
Some LevelOne [4] products (eg WBR-3460A)
Some Linksys products, including the NSLU2 NAS and the WRT54G broadband router.
Motorola A780.
Mvix MX-760HD Media Player.
Netcomm NB1 ADSL Modem.
Netgear routers (eg. DG834G).
Nokia 770, Nokia N800 and Nokia N810.
Some OvisLink products, including the WL-5460AP WiFi AccessPoint and the Evo-DSL04 Modem/Router ADSL2+.
Picotux, advertised as the smallest computer running Linux in the world.
QNAP NAS like TS-101, TS-201,...
Qtopia Greenphone.
Sharp Zaurus.
Sonos Digital Music System.
Sony Digital Video Recorders DHG-HDD250 & DHG-HDD500.
Synology NAS
Telindus 1130 ADSL Router.
Thecus NAS
Some TP-Link products (eg TD-88xx ADSL Routers).
Western Digital My Book.
Zipit Wireless Messenger.

A more complete list can be found on the official website (see external links below).

[edit] GPL lawsuits

What was claimed to be the first US lawsuit over a GPL violation concerned use of BusyBox in an embedded device. The lawsuit^[5], case 07-CV-8205 in the United States District Court for the Southern District of New York was filed on 20 September 2007 by the Software Freedom Law Center on behalf of Andersen and Landley against Monsoon Multimedia Inc., after BusyBox code was discovered in a firmware upgrade and attempts to contact the company had apparently failed. The case was settled with release of the Monsoon version of the source and payment of an undisclosed amount of money to Andersen and Landley.^[6]

On 21 November 2007, the SFLC brought two similar lawsuits on behalf of Andersen and Landley against two more companies, Xterasys (case 07-CV-10456) and High-Gain Antennas (case 07-CV-10455).^[7]^[8] The Xterasys case was settled on December 17 for release of source code used and an undisclosed payment,^[9] and the High-Gain Antennas case on March 6, 2008 for active license compliance and an undisclosed payment.^[10] On 7 December 2007, a case was brought against Verizon Communications over its distribution of firmware for Actiontec routers that it distributes;^[11]^[12] this case was settled March 17, 2008.^[13] Further suits were brought on June 9, 2008 against Bell Microproducts (case 08-CV-5270) and Super Micro Computer (case 08-CV-5269).^[14]