topjohnwu/ndk-busybox

Please see the LICENSE file for details on copying and usage. Please refer to the INSTALL file for instructions on how to build.

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, dhcp, diffutils, e2fsprogs, file, findutils, gawk, grep, inetutils, less, 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. (See 'make help' for more commands.)

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 built-in 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. This uses the CONFIG_PREFIX environment variable to specify where to install, and installs hardlinks or symlinks depending on the configuration preferences. (You can also manually run the install script at "applets/install.sh").

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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.

http://git.busybox.net/busybox/

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

http://www.busybox.net/source.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 (https://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 git changelog.

Note: if you want to compile busybox in a busybox environment you must select CONFIG_DESKTOP.

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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 [email protected]. 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: [email protected]
from: [email protected]
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.

-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, compiled with gcc (the unit-at-a-time optimizations in version 3.4 and later are worth upgrading to get, but older versions should work), and linked against uClibc (0.9.27 or greater) or 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.

There are many other environments out there, in which busybox may build and run just fine. We just don't test them. 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) require 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 (there's still some support code in things like mount.c) 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 will probably accept small self-contained 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 surprised 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.

In 2005 Shaun Jackman has ported busybox to a combination of newlib and libgloss, and some of his patches have been integrated.

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, and v850e. 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 mailing list:

[email protected]

and/or maintainer:

Denys Vlasenko
<[email protected]>