1Building: 2========= 3 4The BusyBox build process is similar to the Linux kernel build: 5 6 make menuconfig # This creates a file called ".config" 7 make # This creates the "busybox" executable 8 make install # or make CONFIG_PREFIX=/path/from/root install 9 10The full list of configuration and install options is available by typing: 11 12 make help 13 14Quick Start: 15============ 16 17The easy way to try out BusyBox for the first time, without having to install 18it, is to enable all features and then use "standalone shell" mode with a 19blank command $PATH. 20 21To enable all features, use "make defconfig", which produces the largest 22general-purpose configuration. (It's allyesconfig minus debugging options, 23optional packaging choices, and a few special-purpose features requiring 24extra configuration to use.) 25 26 make defconfig 27 make 28 PATH= ./busybox ash 29 30Standalone shell mode causes busybox's built-in command shell to run 31any built-in busybox applets directly, without looking for external 32programs by that name. Supplying an empty command path (as above) means 33the only commands busybox can find are the built-in ones. 34 35Note that the standalone shell requires CONFIG_BUSYBOX_EXEC_PATH 36to be set appropriately, depending on whether or not /proc/self/exe is 37available or not. If you do not have /proc, then point that config option 38to the location of your busybox binary, usually /bin/busybox. 39 40Configuring Busybox: 41==================== 42 43Busybox is optimized for size, but enabling the full set of functionality 44still results in a fairly large executable -- more than 1 megabyte when 45statically linked. To save space, busybox can be configured with only the 46set of applets needed for each environment. The minimal configuration, with 47all applets disabled, produces a 4k executable. (It's useless, but very small.) 48 49The manual configurator "make menuconfig" modifies the existing configuration. 50(For systems without ncurses, try "make config" instead.) The two most 51interesting starting configurations are "make allnoconfig" (to start with 52everything disabled and add just what you need), and "make defconfig" (to 53start with everything enabled and remove what you don't need). If menuconfig 54is run without an existing configuration, make defconfig will run first to 55create a known starting point. 56 57Other starting configurations (mostly used for testing purposes) include 58"make allbareconfig" (enables all applets but disables all optional features), 59"make allyesconfig" (enables absolutely everything including debug features), 60and "make randconfig" (produce a random configuration). 61 62Configuring BusyBox produces a file ".config", which can be saved for future 63use. Run "make oldconfig" to bring a .config file from an older version of 64busybox up to date. 65 66Installing Busybox: 67=================== 68 69Busybox is a single executable that can behave like many different commands, 70and BusyBox uses the name it was invoked under to determine the desired 71behavior. (Try "mv busybox ls" and then "./ls -l".) 72 73Installing busybox consists of creating symlinks (or hardlinks) to the busybox 74binary for each applet enabled in busybox, and making sure these symlinks are 75in the shell's command $PATH. Running "make install" creates these symlinks, 76or "make install-hardlinks" creates hardlinks instead (useful on systems with 77a limited number of inodes). This install process uses the file 78"busybox.links" (created by make), which contains the list of enabled applets 79and the path at which to install them. 80 81Installing links to busybox is not always necessary. The special applet name 82"busybox" (or with any optional suffix, such as "busybox-static") uses the 83first argument to determine which applet to behave as, for example 84"./busybox cat LICENSE". (Running the busybox applet with no arguments gives 85a list of all enabled applets.) The standalone shell can also call busybox 86applets without links to busybox under other names in the filesystem. You can 87also configure a standaone install capability into the busybox base applet, 88and then install such links at runtime with one of "busybox --install" (for 89hardlinks) or "busybox --install -s" (for symlinks). 90 91If you enabled the busybox shared library feature (libbusybox.so) and want 92to run tests without installing, set your LD_LIBRARY_PATH accordingly when 93running the executable: 94 95 LD_LIBRARY_PATH=`pwd` ./busybox 96 97Building out-of-tree: 98===================== 99 100By default, the BusyBox build puts its temporary files in the source tree. 101Building from a read-only source tree, or building multiple configurations from 102the same source directory, requires the ability to put the temporary files 103somewhere else. 104 105To build out of tree, cd to an empty directory and configure busybox from there: 106 107 make -f /path/to/source/Makefile defconfig 108 make 109 make install 110 111Alternately, use the O=$BUILDPATH option (with an absolute path) during the 112configuration step, as in: 113 114 make O=/some/empty/directory allyesconfig 115 cd /some/empty/directory 116 make 117 make CONFIG_PREFIX=. install 118 119More Information: 120================= 121 122Se also the busybox FAQ, under the questions "How can I get started using 123BusyBox" and "How do I build a BusyBox-based system?" The BusyBox FAQ is 124available from http://www.busybox.net/FAQ.html or as the file 125docs/busybox.net/FAQ.html in this tarball. 126