busybox

Please see the LICENSE file for details on copying and usage.

What is busybox:

BusyBox combines tiny versions of many common UNIX utilities into a single
small executable. It provides minimalist replacements for most of the
utilities you usually find in bzip2, coreutils, file, findutils, gawk, grep,
inetutils, modutils, net-tools, procps, sed, shadow, sysklogd, sysvinit, tar,
util-linux, and vim. The utilities in BusyBox often have fewer options than
their full-featured cousins; however, the options that are included provide
the expected functionality and behave very much like their larger
counterparts.

BusyBox has been written with size-optimization and limited resources in
mind, both to produce small binaries and to reduce run-time memory usage.
Busybox is also extremely modular so you can easily include or exclude
commands (or features) at compile time. This makes it easy to customize
embedded systems; to create a working system, just add /dev, /etc, and a
Linux kernel. Busybox (usually together with uClibc) has also been used as
a component of "thin client" desktop systems, live-CD distributions, rescue
disks, installers, and so on.

BusyBox provides a fairly complete POSIX environment for any small system,
both embedded environments and more full featured systems concerned about
space. Busybox is slowly working towards implementing the full Single Unix
Specification V3 (http://www.opengroup.org/onlinepubs/009695399/), but isn't
there yet (and for size reasons will probably support at most UTF-8 for
internationalization). We are also interested in passing the Linux Test
Project (http://ltp.sourceforge.net).

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Using busybox:

BusyBox is extremely configurable. This allows you to include only the
components and options you need, thereby reducing binary size. Run 'make
config' or 'make menuconfig' to select the functionality that you wish to
enable.

The behavior of busybox is determined by the name it's called under: as
"cp" it behaves like cp, as "sed" it behaves like sed, and so on. Called
as "busybox" it takes the second argument as the name of the applet to
run (I.E. "./busybox ls -l /proc").

The "standalone shell" mode is an easy way to try out busybox; this is a
command shell that calls the builtin applets without needing them to be
installed in the path. (Note that this requires /proc to be mounted, if
testing from a boot floppy or in a chroot environment.)

The build automatically generates a file "busybox.links", which is used by
'make install' to create symlinks to the BusyBox binary for all compiled in
commands. Use the PREFIX environment variable to specify where to install
the busybox binary and symlink forest. (i.e., 'make PREFIX=/tmp/foo install',
or 'make PREFIX=/tmp/foo install-hardlinks' if you prefer hard links.)

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Downloading the current source code:

Source for the latest released version, as well as daily snapshots, can always
be downloaded from

http://busybox.net/downloads/

You can browse the up to the minute source code and change history online
at:

http://www.busybox.net/cgi-bin/viewcvs.cgi/branches/busybox_1_00_stable/busybox/

Anonymous SVN access is available. For instructions, check out:

http://busybox.net/subversion.html

For those that are actively contributing and would like to check files in,
see:

http://busybox.net/developer.html

The developers also have a bug and patch tracking system
(http://bugs.busybox.net) although posting a bug/patch to the mailing list
is generally a faster way of getting it fixed, and the complete archive of
what happened is the subversion changelog.

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getting help:

when you find you need help, you can check out the busybox mailing list
archives at http://busybox.net/lists/busybox/ or even join
the mailing list if you are interested.

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bugs:

if you find bugs, please submit a detailed bug report to the busybox mailing
list at busybox@busybox.net. a well-written bug report should include a
transcript of a shell session that demonstrates the bad behavior and enables
anyone else to duplicate the bug on their own machine. the following is such
an example:

to: busybox@mail.busybox.net
from: diligent@testing.linux.org
subject: /bin/date doesn't work

package: busybox
version: 1.00

when i execute busybox 'date' it produces unexpected results.
with gnu date i get the following output:

$ date
fri oct 8 14:19:41 mdt 2004

but when i use busybox date i get this instead:

$ date
illegal instruction

i am using debian unstable, kernel version 2.4.25-vrs2 on a netwinder,
and the latest uclibc from cvs. thanks for the wonderful program!

-diligent

note the careful description and use of examples showing not only what
busybox does, but also a counter example showing what an equivalent app
does (or pointing to the text of a relevant standard). Bug reports lacking
such detail may never be fixed... Thanks for understanding.

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Portability:

Busybox is developed and tested on Linux 2.4 and 2.6 kernels, linked
against uClibc (0.9.27 or greater) and glibc (2.2 or greater). In such
an environment, the full set of busybox features should work (and if
anything doesn't we want to know about it so we can fix it). Note that
the 2.6 kernel can be trimmed down considerably with the aid of Matt
Mackall's -tiny work (http://www.selenic.com/tiny-about/).

Since busybox consists of a large number of more or less independent
applets, portability is a question of which features work where. Some
busybox applets (such as cat and rm) are highly portable and likely to work
just about anywhere, while others (such as insmod and losetup) are only
likely to work under fairly recent Linux kernels with recent C libraries.

Earlier versions of Linux and glibc may or may not work, for any given
configuration. Linux 2.2 or earlier should mostly work, but this is no
longer regularly tested and inherently won't support certain features (such
as long files and --bind mounts). The same is true for glibc 2.0 and 2.1,
expect a higher testing and debugging burden using such old infrastructure.
(The busybox developers are not very interested in supporting these older
versions, but can probably be talked into accepting small patches to fix
simple problems.)

Some environments are not recommended. Early versions of uClibc were buggy
and missing many features: upgrade. Linking against libc5 or dietlibc is
not supported and not interesting to the busybox developers. (The first is
obsolete and has no known size or feature advantages over uClibc, the second
has known bugs that its developers have actively refused to fix.) Ancient
Linux kernels (2.0.x and earlier) are similarly uninteresting.

In theory it's possible to use Busybox under other operating systems (such as
MacOS X, Solaris, Cygwin, or the BSD Fork Du Jour). This generally involves
a different kernel and a different C library at the same time. While it
should be possible to port the majority of the code to work in one of
these environments, don't be suprised if it doesn't work out of the box. If
you're into that sort of thing, start small (selecting just a few applets)
and work your way up.

Shaun Jackman has recently (2005) ported busybox to a combination of newlib
and libgloss, and some of his patches have been integrated. This platform
may join glibc/uclibc and Linux as a supported combination with the 1.1
release, but is not supported in 1.0.

Supported hardware:

BusyBox in general will build on any architecture supported by gcc. We
support both 32 and 64 bit platforms, and both big and little endian
systems.

Under 2.4 Linux kernels, kernel module loading was implemented in a
platform-specific manner. Busybox's insmod utility has been reported to
work under ARM, CRIS, H8/300, x86, ia64, x86_64, m68k, MIPS, PowerPC, S390,
SH3/4/5, Sparc, v850e, and x86_64. Anything else probably won't work.

The module loading mechanism for the 2.6 kernel is much more generic, and
we believe 2.6.x kernel module loading support should work on all
architectures supported by the kernel.

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Please feed suggestions, bug reports, insults, and bribes back to the busybox
maintainer:
Erik Andersen