| 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 CONFIG_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. |
| |
| To enable all features, use "make defconfig", which produces the largest |
| general-purpose configuration. It's allyesconfig minus debugging options, |
| optional packaging choices, and a few special-purpose features requiring |
| extra configuration to use. Then enable "standalone shell" feature: |
| |
| make defconfig |
| make menuconfig |
| # select Busybox Settings |
| # then General Configuration |
| # then exec prefers applets |
| # exit back to top level menu |
| # select Shells |
| # then Standalone shell |
| # exit back to top level menu |
| # exit and save new configuration |
| # OR |
| # use these commands to modify .config directly: |
| sed -e 's/.*FEATURE_PREFER_APPLETS.*/CONFIG_FEATURE_PREFER_APPLETS=y/' -i .config |
| sed -e 's/.*FEATURE_SH_STANDALONE.*/CONFIG_FEATURE_SH_STANDALONE=y/' -i .config |
| 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 CONFIG_BUSYBOX_EXEC_PATH |
| to be set appropriately, depending on whether or not /proc/self/exe is |
| available or not. If you do not have /proc, then point that config option |
| to the location of your busybox binary, usually /bin/busybox. |
| |
| 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 configurator "make menuconfig" modifies the existing configuration. |
| (For systems without ncurses, try "make config" instead.) The two most |
| interesting starting configurations are "make allnoconfig" (to start with |
| everything disabled and add just what you need), and "make defconfig" (to |
| start with everything enabled and remove what you don't need). If menuconfig |
| is run without an existing configuration, make defconfig will run first to |
| create a known starting point. |
| |
| Other starting configurations (mostly used for testing purposes) include |
| "make allbareconfig" (enables all applets but disables all optional features), |
| "make allyesconfig" (enables absolutely everything including debug features), |
| and "make randconfig" (produce a random configuration). The configs/ directory |
| contains a number of additional configuration files ending in _defconfig which |
| are useful in specific cases. "make help" will list them. |
| |
| Configuring BusyBox produces a file ".config", which can be saved for future |
| use. Run "make oldconfig" to bring a .config file from an older version of |
| busybox up to date. |
| |
| 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 $PATH. Running "make install" creates these symlinks, |
| or "make install-hardlinks" creates hardlinks instead (useful on systems with |
| a limited number of inodes). This install process uses the file |
| "busybox.links" (created by make), which contains the list of enabled applets |
| and the path at which to install them. |
| |
| Installing links to busybox is not always necessary. The special applet name |
| "busybox" (or with any optional suffix, such as "busybox-static") uses the |
| first argument to determine which applet to behave as, for example |
| "./busybox cat LICENSE". (Running the busybox applet with no arguments gives |
| a list of all enabled applets.) The standalone shell can also call busybox |
| applets without links to busybox under other names in the filesystem. You can |
| also configure a standalone install capability into the busybox base applet, |
| and then install such links at runtime with one of "busybox --install" (for |
| hardlinks) or "busybox --install -s" (for symlinks). |
| |
| If you enabled the busybox shared library feature (libbusybox.so) and want |
| to run tests without installing, set your LD_LIBRARY_PATH accordingly when |
| running the executable: |
| |
| LD_LIBRARY_PATH=`pwd` ./busybox |
| |
| Building out-of-tree: |
| ===================== |
| |
| By default, the BusyBox build puts its temporary files in the source tree. |
| Building from a read-only source tree, or building multiple configurations from |
| the same source directory, requires the ability to put the temporary files |
| somewhere else. |
| |
| To build out of tree, cd to an empty directory and configure busybox from there: |
| |
| make KBUILD_SRC=/path/to/source -f /path/to/source/Makefile defconfig |
| make |
| make install |
| |
| Alternately, use the O=$BUILDPATH option (with an absolute path) during the |
| configuration step, as in: |
| |
| make O=/some/empty/directory allyesconfig |
| cd /some/empty/directory |
| make |
| make CONFIG_PREFIX=. install |
| |
| 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 |