Building: ========= The BusyBox build process is similar to the Linux kernel build: make menuconfig # This creates a file called ".config" make # This creates the "busybox" executable make install # or make PREFIX=/path/from/root install The full list of configuration and install options is available by typing: make help Quick Start: ============ The easy way to try out BusyBox for the first time, without having to install it, is to enable all features and then use "standalone shell" mode with a blank command $PATH: make allyesconfig make PATH= ./busybox ash Standalone shell mode causes busybox's built-in command shell to run any built-in busybox applets directly, without looking for external programs by that name. Supplying an empty command path (as above) means the only commands busybox can find are the built-in ones. (Note that the standalone shell requires the /proc directory to function.) Configuring Busybox: ==================== Busybox is optimized for size, but enabling the full set of functionality still results in a fairly large executable (more than 1 megabyte when statically linked). To save space, busybox can be configured with only the set of applets needed for each environment. The minimal configuration, with all applets disabled, produces a 4k executable. (It's useless, but very small.) The manual configurators "make config" and "make menuconfig" modify the existing configuration. Quick ways to get starting configurations include "make allyesconfig" (enables almost all options), "make allnoconfig" (disables all options), "make allbaseconfig" (enables all applets but disables all optional features), and "make defconfig" (reset to defaults). Configuring BusyBox produces a file ".config", which can be saved for future use. Installing Busybox: =================== Busybox is a single executable that can behave like many different commands, and BusyBox uses the name it was invoked under to determine the desired behavior. (Try "mv busybox ls" and then "./ls -l".) Installing busybox consists of creating symlinks (or hardlinks) to the busybox binary for each applet enabled in busybox, and making sure these symlinks are in the shell's command $PATH. Running "make install" creates these symlinks, or "make install-hardlinks" creates hardlinks instead (useful on systems with a limited number of inodes). This install process uses the file "busybox.links" (created by make), which contains the list of enabled applets and the path at which to install them. Installing links to busybox is not always necessary. The special applet name "busybox" (or with any optional suffix, such as "busybox-static") uses the first argument to determine which applet to behave as, for example "./busybox cat LICENSE". (Running the busybox applet with no arguments gives a list of all enabled applets.) The standalone shell can also call busybox applets without links to busybox under other names in the filesystem. You can also configure a standaone install capability into the busybox base applet, and then install such links at runtime with one of "busybox --install" (for hardlinks) or "busybox --install -s" (for symlinks). If you built busybox as shared object which uses libbusybox.so and have not yet installed the binary but want to run tests, then set your LD_LIBRARY_PATH accordingly before running the executable: export LD_LIBRARY_PATH=`pwd` ./busybox Building out-of-tree: ===================== By default, the BusyBox build puts its temporary files in the source tree. Building from a read-only source tree, or to building multiple configurations from the same source directory, requires the ability to put the temporary files somewhere else. To build out of tree, cd to the empty directory and do this instead: make -f /path/to/source/Makefile allyesconfig make make install Alternately, use the O=$BUILDPATH option during the configuration step, as in: make O=/some/empty/directory allyesconfig cd /some/empty/directory make make PREFIX=. install (Note, O= requires an absolute path.) More Information: ================= Se also the busybox FAQ, under the questions "How can I get started using BusyBox" and "How do I build a BusyBox-based system?" The BusyBox FAQ is available from http://www.busybox.net/FAQ.html or as the file docs/busybox.net/FAQ.html in this tarball.