1 | Building:
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2 | =========
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3 |
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4 | The BusyBox build process is similar to the Linux kernel build:
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5 |
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6 | make menuconfig # This creates a file called ".config"
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7 | make # This creates the "busybox" executable
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8 | make install # or make CONFIG_PREFIX=/path/from/root install
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9 |
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10 | The full list of configuration and install options is available by typing:
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11 |
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12 | make help
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13 |
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14 | Quick Start:
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15 | ============
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16 |
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17 | The easy way to try out BusyBox for the first time, without having to install
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18 | it, is to enable all features and then use "standalone shell" mode with a
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19 | blank command $PATH.
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20 |
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21 | To enable all features, use "make defconfig", which produces the largest
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22 | general-purpose configuration. It's allyesconfig minus debugging options,
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23 | optional packaging choices, and a few special-purpose features requiring
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24 | extra configuration to use. Then enable "standalone shell" feature:
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25 |
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26 | make defconfig
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27 | make menuconfig
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28 | # select Busybox Settings
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29 | # then General Configuration
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30 | # then exec prefers applets
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31 | # exit back to top level menu
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32 | # select Shells
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33 | # then Standalone shell
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34 | # exit back to top level menu
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35 | # exit and save new configuration
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36 | # OR
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37 | # use these commands to modify .config directly:
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38 | sed -e 's/.*FEATURE_PREFER_APPLETS.*/CONFIG_FEATURE_PREFER_APPLETS=y/' -i .config
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39 | sed -e 's/.*FEATURE_SH_STANDALONE.*/CONFIG_FEATURE_SH_STANDALONE=y/' -i .config
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40 | make
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41 | PATH= ./busybox ash
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42 |
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43 | Standalone shell mode causes busybox's built-in command shell to run
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44 | any built-in busybox applets directly, without looking for external
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45 | programs by that name. Supplying an empty command path (as above) means
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46 | the only commands busybox can find are the built-in ones.
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47 |
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48 | Note that the standalone shell requires CONFIG_BUSYBOX_EXEC_PATH
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49 | to be set appropriately, depending on whether or not /proc/self/exe is
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50 | available or not. If you do not have /proc, then point that config option
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51 | to the location of your busybox binary, usually /bin/busybox.
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52 |
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53 | Configuring Busybox:
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54 | ====================
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55 |
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56 | Busybox is optimized for size, but enabling the full set of functionality
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57 | still results in a fairly large executable -- more than 1 megabyte when
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58 | statically linked. To save space, busybox can be configured with only the
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59 | set of applets needed for each environment. The minimal configuration, with
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60 | all applets disabled, produces a 4k executable. (It's useless, but very small.)
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61 |
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62 | The manual configurator "make menuconfig" modifies the existing configuration.
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63 | (For systems without ncurses, try "make config" instead.) The two most
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64 | interesting starting configurations are "make allnoconfig" (to start with
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65 | everything disabled and add just what you need), and "make defconfig" (to
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66 | start with everything enabled and remove what you don't need). If menuconfig
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67 | is run without an existing configuration, make defconfig will run first to
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68 | create a known starting point.
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69 |
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70 | Other starting configurations (mostly used for testing purposes) include
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71 | "make allbareconfig" (enables all applets but disables all optional features),
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72 | "make allyesconfig" (enables absolutely everything including debug features),
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73 | and "make randconfig" (produce a random configuration).
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74 |
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75 | Configuring BusyBox produces a file ".config", which can be saved for future
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76 | use. Run "make oldconfig" to bring a .config file from an older version of
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77 | busybox up to date.
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78 |
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79 | Installing Busybox:
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80 | ===================
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81 |
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82 | Busybox is a single executable that can behave like many different commands,
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83 | and BusyBox uses the name it was invoked under to determine the desired
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84 | behavior. (Try "mv busybox ls" and then "./ls -l".)
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85 |
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86 | Installing busybox consists of creating symlinks (or hardlinks) to the busybox
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87 | binary for each applet enabled in busybox, and making sure these symlinks are
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88 | in the shell's command $PATH. Running "make install" creates these symlinks,
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89 | or "make install-hardlinks" creates hardlinks instead (useful on systems with
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90 | a limited number of inodes). This install process uses the file
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91 | "busybox.links" (created by make), which contains the list of enabled applets
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92 | and the path at which to install them.
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93 |
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94 | Installing links to busybox is not always necessary. The special applet name
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95 | "busybox" (or with any optional suffix, such as "busybox-static") uses the
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96 | first argument to determine which applet to behave as, for example
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97 | "./busybox cat LICENSE". (Running the busybox applet with no arguments gives
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98 | a list of all enabled applets.) The standalone shell can also call busybox
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99 | applets without links to busybox under other names in the filesystem. You can
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100 | also configure a standaone install capability into the busybox base applet,
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101 | and then install such links at runtime with one of "busybox --install" (for
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102 | hardlinks) or "busybox --install -s" (for symlinks).
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103 |
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104 | If you enabled the busybox shared library feature (libbusybox.so) and want
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105 | to run tests without installing, set your LD_LIBRARY_PATH accordingly when
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106 | running the executable:
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107 |
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108 | LD_LIBRARY_PATH=`pwd` ./busybox
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109 |
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110 | Building out-of-tree:
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111 | =====================
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112 |
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113 | By default, the BusyBox build puts its temporary files in the source tree.
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114 | Building from a read-only source tree, or building multiple configurations from
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115 | the same source directory, requires the ability to put the temporary files
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116 | somewhere else.
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117 |
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118 | To build out of tree, cd to an empty directory and configure busybox from there:
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119 |
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120 | make KBUILD_SRC=/path/to/source -f /path/to/source/Makefile defconfig
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121 | make
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122 | make install
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123 |
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124 | Alternately, use the O=$BUILDPATH option (with an absolute path) during the
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125 | configuration step, as in:
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126 |
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127 | make O=/some/empty/directory allyesconfig
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128 | cd /some/empty/directory
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129 | make
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130 | make CONFIG_PREFIX=. install
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131 |
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132 | More Information:
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133 | =================
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134 |
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135 | Se also the busybox FAQ, under the questions "How can I get started using
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136 | BusyBox" and "How do I build a BusyBox-based system?" The BusyBox FAQ is
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137 | available from http://www.busybox.net/FAQ.html
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