koalaman/toybox

Toybox: all-in-one Linux command line.

--- Getting started

You can download static binaries for various targets from:

http://landley.net/toybox/bin

The special name "." indicates the current directory (just like ".." means the parent directory), and you can run a program that isn't in the $PATH by specifying a path to it, so this should work:

wget http://landley.net/toybox/bin/toybox-x86_64 chmod +x toybox-x86_64 ./toybox-x86_64 echo hello world

--- Building toybox

Type "make help" for build instructions.

Toybox uses the "make menuconfig; make; make install" idiom same as the Linux kernel. Usually you want something like:

make defconfig make make install

Or maybe:

LDFLAGS="--static" CROSS_COMPILE=armv5l- make defconfig toybox PREFIX=/path/to/root/filesystem/bin make install_flat

The file "configure" defines default values for many environment variables that control the toybox build; if you set a value for any of these, your value is used instead of the default in that file.

The CROSS_COMPILE argument above is optional, the default builds a version of toybox to run on the current machine. Cross compiling requires an appropriately prefixed cross compiler toolchain, several example toolchains are available at:

http://landley.net/aboriginal/bin

For the "CROSS_COMPILE=armv5l-" example above, download cross-compiler-armv5l.tar.bz2, extract it, and add its "bin" subdirectory to your $PATH. (And yes, the trailing - is significant, because the prefix includes a dash.)

For more about cross compiling, see:

http://landley.net/writing/docs/cross-compiling.html http://landley.net/aboriginal/architectures.html

For a more thorough description of the toybox build process, see http://landley.net/toybox/code.html#building

--- Using toybox

The toybox build produces a multicall binary, a "swiss-army-knife" program that acts differently depending on the name it was called by (cp, mv, cat...). Installing toybox adds symlinks for each command name to the $PATH.

The special "toybox" command treats its first argument as the command to run. With no arguments, it lists available commands. This allows you to use toybox without installing it. This is the only command that can have an arbitrary suffix (hence "toybox-armv5l").

The "help" command provides information about each command (ala "help cat").

--- Configuring toybox

It works like the Linux kernel: allnoconfig, defconfig, and menuconfig edit a ".config" file that selects which features to include in the resulting binary. You can save and re-use your .config file, although may want to run "make oldconfig" to re-run the dependency resolver when migrating to new versions.

The maximum sane configuration is "make defconfig": allyesconfig isn't recommended for toybox because it enables unfinished commands and debug code.

--- Creating a Toybox-based Linux system

Toybox is not a complete operating system, it's a program that runs under an operating system. Booting a simple system to a shell prompt requires three packages: an operating system kernel (Linux*) to drive the hardware, one or more programs for the system to run (toybox), and a C library ("libc") to tie them together (toybox has been tested with musl, uClibc, glibc, and bionic).

The C library is part of a "toolchain", which is an integrated suite of compiler, assembler, and linker, plus the standard headers and libraries necessary to build C programs. (And miscellaneous binaries like nm and objdump.)

Static linking (with the --static option) copies the shared library contents into the program, resulting in larger but more portable programs, which can run even if they're the only file in the filesystem. Otherwise, the "dynamically" linked programs require the library files to be present on the target system ("man ldd" and "man ld.so" for details).

An example toybox-based system is Aboriginal Linux:

http://landley.net/aboriginal/about.html

That's designed to run under qemu, emulating several different hardware architectures (x86, x86-64, arm, mips, sparc, powerpc, sh4). Each toybox release is regression tested by building Linux From Scratch under this toybox-based system on each supported architecture, using QEMU to emulate big and little endian systems with different word size and alignment requirements. (The eventual goal is to replace Linux From Scratch with the Android Open Source Project.)

• Or something providing the same API such as FreeBSD's Linux emulation layer.

--- Presentations

1. "Why Toybox?" talk at the Embedded Linux Conference in 2013

   video: http://youtu.be/SGmtP5Lg_t0 outline: http://landley.net/talks/celf-2013.txt linked from http://landley.net/toybox/ in nav bar on left as "Why is it?"

   • march 21, 2013 entry has section links.

2. "Why Public Domain?" The rise and fall of copyleft, Ohio LinuxFest 2013

   audio: https://archive.org/download/OhioLinuxfest2013/24-Rob_Landley-The_Rise_and_Fall_of_Copyleft.mp3 outline: http://landley.net/talks/ohio-2013.txt

3. Why did I do Aboriginal Linux (which led me here)

   260 slide presentation: https://speakerdeck.com/landley/developing-for-non-x86-targets-using-qemu

   How and why to make android self-hosting: http://landley.net/aboriginal/about.html#selfhost

4. What's new with toybox (ELC 2015 status update):

   video: http://elinux.org/ELC_2015_Presentations outline: http://landley.net/talks/celf-2015.txt

--- Contributing

The three important URLs for communicating with the toybox project are:

web page: http://landley.net/toybox

mailing list: http://lists.landley.net/listinfo.cgi/toybox-landley.net

git repo: http://github.com/landley/toybox

The maintainer prefers patches be sent to the mailing list. If you use git, the easy thing to do is:

git format-patch -1 $HASH

Then send a file attachment. The list holds messages from non-subscribers for moderation, but I usually get to them in a day or two.

Although I do accept pull requests on github, I download the patches and apply them with "git am" (which avoids gratuitous merge commits). Closing the pull request is then the submitter's responsibility.

If I haven't responded to your patch after one week, feel free to remind me of it.

Android's policy for toybox patches is that non-build patches should go upstream first (into vanilla toybox, with discussion on the toybox mailing list) and then be pulled into android's toybox repo from there. (They generally resync on fridays). The exception is patches to their build scripts (Android.mk and the checked-in generated/* files) which go directly to AOSP.