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. Then enable "standalone shell" feature: 25 26 make defconfig 27 make menuconfig 28 # select Busybox Settings 29 # then General Configuration 30 # then exec prefers applets 31 # exit back to top level menu 32 # select Shells 33 # then Standalone shell 34 # exit back to top level menu 35 # exit and save new configuration 36 # OR 37 # use these commands to modify .config directly: 38 sed -e 's/.*FEATURE_PREFER_APPLETS.*/CONFIG_FEATURE_PREFER_APPLETS=y/' -i .config 39 sed -e 's/.*FEATURE_SH_STANDALONE.*/CONFIG_FEATURE_SH_STANDALONE=y/' -i .config 40 make 41 PATH= ./busybox ash 42 43Standalone shell mode causes busybox's built-in command shell to run 44any built-in busybox applets directly, without looking for external 45programs by that name. Supplying an empty command path (as above) means 46the only commands busybox can find are the built-in ones. 47 48Note that the standalone shell requires CONFIG_BUSYBOX_EXEC_PATH 49to be set appropriately, depending on whether or not /proc/self/exe is 50available or not. If you do not have /proc, then point that config option 51to the location of your busybox binary, usually /bin/busybox. 52 53Configuring Busybox: 54==================== 55 56Busybox is optimized for size, but enabling the full set of functionality 57still results in a fairly large executable -- more than 1 megabyte when 58statically linked. To save space, busybox can be configured with only the 59set of applets needed for each environment. The minimal configuration, with 60all applets disabled, produces a 4k executable. (It's useless, but very small.) 61 62The manual configurator "make menuconfig" modifies the existing configuration. 63(For systems without ncurses, try "make config" instead.) The two most 64interesting starting configurations are "make allnoconfig" (to start with 65everything disabled and add just what you need), and "make defconfig" (to 66start with everything enabled and remove what you don't need). If menuconfig 67is run without an existing configuration, make defconfig will run first to 68create a known starting point. 69 70Other starting configurations (mostly used for testing purposes) include 71"make allbareconfig" (enables all applets but disables all optional features), 72"make allyesconfig" (enables absolutely everything including debug features), 73and "make randconfig" (produce a random configuration). 74 75Configuring BusyBox produces a file ".config", which can be saved for future 76use. Run "make oldconfig" to bring a .config file from an older version of 77busybox up to date. 78 79Installing Busybox: 80=================== 81 82Busybox is a single executable that can behave like many different commands, 83and BusyBox uses the name it was invoked under to determine the desired 84behavior. (Try "mv busybox ls" and then "./ls -l".) 85 86Installing busybox consists of creating symlinks (or hardlinks) to the busybox 87binary for each applet enabled in busybox, and making sure these symlinks are 88in the shell's command $PATH. Running "make install" creates these symlinks, 89or "make install-hardlinks" creates hardlinks instead (useful on systems with 90a limited number of inodes). This install process uses the file 91"busybox.links" (created by make), which contains the list of enabled applets 92and the path at which to install them. 93 94Installing links to busybox is not always necessary. The special applet name 95"busybox" (or with any optional suffix, such as "busybox-static") uses the 96first argument to determine which applet to behave as, for example 97"./busybox cat LICENSE". (Running the busybox applet with no arguments gives 98a list of all enabled applets.) The standalone shell can also call busybox 99applets without links to busybox under other names in the filesystem. You can 100also configure a standaone install capability into the busybox base applet, 101and then install such links at runtime with one of "busybox --install" (for 102hardlinks) or "busybox --install -s" (for symlinks). 103 104If you enabled the busybox shared library feature (libbusybox.so) and want 105to run tests without installing, set your LD_LIBRARY_PATH accordingly when 106running the executable: 107 108 LD_LIBRARY_PATH=`pwd` ./busybox 109 110Building out-of-tree: 111===================== 112 113By default, the BusyBox build puts its temporary files in the source tree. 114Building from a read-only source tree, or building multiple configurations from 115the same source directory, requires the ability to put the temporary files 116somewhere else. 117 118To build out of tree, cd to an empty directory and configure busybox from there: 119 120 make KBUILD_SRC=/path/to/source -f /path/to/source/Makefile defconfig 121 make 122 make install 123 124Alternately, use the O=$BUILDPATH option (with an absolute path) during the 125configuration step, as in: 126 127 make O=/some/empty/directory allyesconfig 128 cd /some/empty/directory 129 make 130 make CONFIG_PREFIX=. install 131 132More Information: 133================= 134 135Se also the busybox FAQ, under the questions "How can I get started using 136BusyBox" and "How do I build a BusyBox-based system?" The BusyBox FAQ is 137available from http://www.busybox.net/FAQ.html 138