1Please see the LICENSE file for details on copying and usage.
   2Please refer to the INSTALL file for instructions on how to build.
   4What is busybox:
   6  BusyBox combines tiny versions of many common UNIX utilities into a single
   7  small executable.  It provides minimalist replacements for most of the
   8  utilities you usually find in bzip2, coreutils, dhcp, diffutils, e2fsprogs,
   9  file, findutils, gawk, grep, inetutils, less, modutils, net-tools, procps,
  10  sed, shadow, sysklogd, sysvinit, tar, util-linux, and vim.  The utilities
  11  in BusyBox often have fewer options than their full-featured cousins;
  12  however, the options that are included provide the expected functionality
  13  and behave very much like their larger counterparts.
  15  BusyBox has been written with size-optimization and limited resources in
  16  mind, both to produce small binaries and to reduce run-time memory usage.
  17  Busybox is also extremely modular so you can easily include or exclude
  18  commands (or features) at compile time.  This makes it easy to customize
  19  embedded systems; to create a working system, just add /dev, /etc, and a
  20  Linux kernel.  Busybox (usually together with uClibc) has also been used as
  21  a component of "thin client" desktop systems, live-CD distributions, rescue
  22  disks, installers, and so on.
  24  BusyBox provides a fairly complete POSIX environment for any small system,
  25  both embedded environments and more full featured systems concerned about
  26  space.  Busybox is slowly working towards implementing the full Single Unix
  27  Specification V3 (http://www.opengroup.org/onlinepubs/009695399/), but isn't
  28  there yet (and for size reasons will probably support at most UTF-8 for
  29  internationalization).  We are also interested in passing the Linux Test
  30  Project (http://ltp.sourceforge.net).
  34Using busybox:
  36  BusyBox is extremely configurable.  This allows you to include only the
  37  components and options you need, thereby reducing binary size.  Run 'make
  38  config' or 'make menuconfig' to select the functionality that you wish to
  39  enable.  (See 'make help' for more commands.)
  41  The behavior of busybox is determined by the name it's called under: as
  42  "cp" it behaves like cp, as "sed" it behaves like sed, and so on.  Called
  43  as "busybox" it takes the second argument as the name of the applet to
  44  run (I.E. "./busybox ls -l /proc").
  46  The "standalone shell" mode is an easy way to try out busybox; this is a
  47  command shell that calls the built-in applets without needing them to be
  48  installed in the path.  (Note that this requires /proc to be mounted, if
  49  testing from a boot floppy or in a chroot environment.)
  51  The build automatically generates a file "busybox.links", which is used by
  52  'make install' to create symlinks to the BusyBox binary for all compiled in
  53  commands.  This uses the CONFIG_PREFIX environment variable to specify
  54  where to install, and installs hardlinks or symlinks depending
  55  on the configuration preferences.  (You can also manually run
  56  the install script at "applets/install.sh").
  60Downloading the current source code:
  62  Source for the latest released version, as well as daily snapshots, can always
  63  be downloaded from
  65    http://busybox.net/downloads/
  67  You can browse the up to the minute source code and change history online.
  69    http://git.busybox.net/busybox/
  71  Anonymous GIT access is available.  For instructions, check out:
  73    http://www.busybox.net/source.html
  75  For those that are actively contributing and would like to check files in,
  76  see:
  78    http://busybox.net/developer.html
  80  The developers also have a bug and patch tracking system
  81  (https://bugs.busybox.net) although posting a bug/patch to the mailing list
  82  is generally a faster way of getting it fixed, and the complete archive of
  83  what happened is the git changelog.
  85  Note: if you want to compile busybox in a busybox environment you must
  86  select CONFIG_DESKTOP.
  90Getting help:
  92  when you find you need help, you can check out the busybox mailing list
  93  archives at http://busybox.net/lists/busybox/ or even join
  94  the mailing list if you are interested.
 100  if you find bugs, please submit a detailed bug report to the busybox mailing
 101  list at busybox@busybox.net.  a well-written bug report should include a
 102  transcript of a shell session that demonstrates the bad behavior and enables
 103  anyone else to duplicate the bug on their own machine. the following is such
 104  an example:
 106    to: busybox@busybox.net
 107    from: diligent@testing.linux.org
 108    subject: /bin/date doesn't work
 110    package: busybox
 111    version: 1.00
 113    when i execute busybox 'date' it produces unexpected results.
 114    with gnu date i get the following output:
 116        $ date
 117        fri oct  8 14:19:41 mdt 2004
 119    but when i use busybox date i get this instead:
 121        $ date
 122        illegal instruction
 124    i am using debian unstable, kernel version 2.4.25-vrs2 on a netwinder,
 125    and the latest uclibc from cvs.
 127        -diligent
 129  note the careful description and use of examples showing not only what
 130  busybox does, but also a counter example showing what an equivalent app
 131  does (or pointing to the text of a relevant standard).  Bug reports lacking
 132  such detail may never be fixed...  Thanks for understanding.
 138  Busybox is developed and tested on Linux 2.4 and 2.6 kernels, compiled
 139  with gcc (the unit-at-a-time optimizations in version 3.4 and later are
 140  worth upgrading to get, but older versions should work), and linked against
 141  uClibc (0.9.27 or greater) or glibc (2.2 or greater).  In such an
 142  environment, the full set of busybox features should work, and if
 143  anything doesn't we want to know about it so we can fix it.
 145  There are many other environments out there, in which busybox may build
 146  and run just fine.  We just don't test them.  Since busybox consists of a
 147  large number of more or less independent applets, portability is a question
 148  of which features work where.  Some busybox applets (such as cat and rm) are
 149  highly portable and likely to work just about anywhere, while others (such as
 150  insmod and losetup) require recent Linux kernels with recent C libraries.
 152  Earlier versions of Linux and glibc may or may not work, for any given
 153  configuration.  Linux 2.2 or earlier should mostly work (there's still
 154  some support code in things like mount.c) but this is no longer regularly
 155  tested, and inherently won't support certain features (such as long files
 156  and --bind mounts).  The same is true for glibc 2.0 and 2.1: expect a higher
 157  testing and debugging burden using such old infrastructure.  (The busybox
 158  developers are not very interested in supporting these older versions, but
 159  will probably accept small self-contained patches to fix simple problems.)
 161  Some environments are not recommended.  Early versions of uClibc were buggy
 162  and missing many features: upgrade.  Linking against libc5 or dietlibc is
 163  not supported and not interesting to the busybox developers.  (The first is
 164  obsolete and has no known size or feature advantages over uClibc, the second
 165  has known bugs that its developers have actively refused to fix.)  Ancient
 166  Linux kernels (2.0.x and earlier) are similarly uninteresting.
 168  In theory it's possible to use Busybox under other operating systems (such as
 169  MacOS X, Solaris, Cygwin, or the BSD Fork Du Jour).  This generally involves
 170  a different kernel and a different C library at the same time.  While it
 171  should be possible to port the majority of the code to work in one of
 172  these environments, don't be surprised if it doesn't work out of the box.  If
 173  you're into that sort of thing, start small (selecting just a few applets)
 174  and work your way up.
 176  In 2005 Shaun Jackman has ported busybox to a combination of newlib
 177  and libgloss, and some of his patches have been integrated.
 179Supported hardware:
 181  BusyBox in general will build on any architecture supported by gcc.  We
 182  support both 32 and 64 bit platforms, and both big and little endian
 183  systems.
 185  Under 2.4 Linux kernels, kernel module loading was implemented in a
 186  platform-specific manner.  Busybox's insmod utility has been reported to
 187  work under ARM, CRIS, H8/300, x86, ia64, x86_64, m68k, MIPS, PowerPC, S390,
 188  SH3/4/5, Sparc, and v850e.  Anything else probably won't work.
 190  The module loading mechanism for the 2.6 kernel is much more generic, and
 191  we believe 2.6.x kernel module loading support should work on all
 192  architectures supported by the kernel.
 196Please feed suggestions, bug reports, insults, and bribes back to the busybox
 197mailing list:
 199        busybox@busybox.net
 201and/or maintainer:
 203        Denys Vlasenko
 204        <vda.linux@googlemail.com>