# For a description of the syntax of this configuration file,
# see scripts/kbuild/config-language.txt.
mainmenu "BusyBox Configuration"
menu "Busybox Settings"
menu "General Configuration"
bool "See lots more (probably unnecessary) configuration options."
Some BusyBox applets have more configuration options than anyone
will ever care about. To avoid drowining people in complexity, most
of the applet features that can be set to a sane default value are
hidden, unless you hit the above switch.
This is better than to telling people to edit the busybox source
code, but not by much.
You have been warned.
bool "Enable options for full-blown desktop systems"
Enable options and features which are not essential.
Select this only if you plan to use busybox on full-blown
desktop machine with common Linux distro, not on an embedded box.
prompt "Buffer allocation policy"
depends on NITPICK
There are 3 ways BusyBox can handle buffer allocations:
- Use malloc. This costs code size for the call to xmalloc.
- Put them on stack. For some very small machines with limited stack
space, this can be deadly. For most folks, this works just fine.
- Put them in BSS. This works beautifully for computers with a real
MMU (and OS support), but wastes runtime RAM for uCLinux. This
behavior was the only one available for BusyBox versions 0.48 and
bool "Allocate with Malloc"
bool "Allocate on the Stack"
bool "Allocate in the .bss section"
bool "Show terse applet usage messages"
All BusyBox applets will show help messages when invoked with
wrong arguments. You can turn off printing these terse usage
messages if you say no here.
This will save you up to 7k.
bool "Show verbose applet usage messages"
All BusyBox applets will show more verbose help messages when
busybox is invoked with --help. This will add a lot of text to the
busybox binary. In the default configuration, this will add about
13k, but it can add much more depending on your configuration.
bool "Store applet usage messages in compressed form"
depends on SHOW_USAGE
Store usage messages in compressed form, uncompress them on-the-fly
when <applet> --help is called.
If you have a really tiny busybox with few applets enabled (and
bunzip2 isn't one of them), the overhead of the decompressor might
be noticeable. Also, if you run executables directly from ROM
and have very little memory, this might not be a win. Otherwise,
you probably want this.
bool "Support --install [-s] to install applet links at runtime"
Enable 'busybox --install [-s]' support. This will allow you to use
busybox at runtime to create hard links or symlinks for all the
applets that are compiled into busybox.
bool "Enable locale support (system needs locale for this to work)"
Enable this if your system has locale support and you would like
busybox to support locale settings.
bool "Enable support for --long-options"
Enable this if you want busybox applets to use the gnu --long-option
style, in addition to single character -a -b -c style options.
bool "Use the devpts filesystem for Unix98 PTYs"
Enable if you want BusyBox to use Unix98 PTY support. If enabled,
busybox will use /dev/ptmx for the master side of the pseudoterminal
and /dev/pts/<number> for the slave side. Otherwise, BSD style
/dev/ttyp<number> will be used. To use this option, you should have
bool "Clean up all memory before exiting (usually not needed)"
depends on NITPICK
As a size optimization, busybox normally exits without explicitly
freeing dynamically allocated memory or closing files. This saves
space since the OS will clean up for us, but it can confuse debuggers
like valgrind, which report tons of memory and resource leaks.
Don't enable this unless you have a really good reason to clean
things up manually.
bool "Support writing pidfiles"
This option makes some applets (e.g. crond, syslogd, inetd) write
a pidfile in /var/run. Some applications rely on them.
bool "Support for SUID/SGID handling"
With this option you can install the busybox binary belonging
to root with the suid bit set, and it'll and it'll automatically drop
priviledges for applets that don't need root access.
If you're really paranoid and don't want to do this, build two
busybox binaries with different applets in them (and the appropriate
symlinks pointing to each binary), and only set the suid bit on the
one that needs it. The applets currently marked to need the suid bit
are login, passwd, su, ping, traceroute, crontab, dnsd, ipcrm, ipcs,
bool "Runtime SUID/SGID configuration via /etc/busybox.conf"
default n if FEATURE_SUID
depends on FEATURE_SUID
Allow the SUID / SGID state of an applet to be determined at runtime
by checking /etc/busybox.conf. (This is sort of a poor man's sudo.)
The format of this file is as follows:
<applet> = [Ssx-][Ssx-][x-] (<username>|<uid>).(<groupname>|<gid>)
An example might help:
su = ssx root.0 # applet su can be run by anyone and runs with euid=0/egid=0
su = ssx # exactly the same
mount = sx- root.disk # applet mount can be run by root and members of group disk
# and runs with euid=0
cp = --- # disable applet cp for everyone
The file has to be owned by user root, group root and has to be
writeable only by root:
(chown 0.0 /etc/busybox.conf; chmod 600 /etc/busybox.conf)
The busybox executable has to be owned by user root, group
root and has to be setuid root for this to work:
(chown 0.0 /bin/busybox; chmod 4755 /bin/busybox)
Robert 'sandman' Griebl has more information here:
<url: http://www.softforge.de/bb/suid.html >.
bool "Suppress warning message if /etc/busybox.conf is not readable"
depends on FEATURE_SUID_CONFIG
/etc/busybox.conf should be readable by the user needing the SUID, check
this option to avoid users to be notified about missing permissions.
bool "Support NSA Security Enhanced Linux"
Enable support for SELinux in applets ls, ps, and id. Also provide
the option of compiling in SELinux applets.
If you do not have a complete SELinux userland installed, this stuff
will not compile. Go visit
to download the necessary stuff to allow busybox to compile with
this option enabled. Specifially, libselinux 1.28 or better is
directly required by busybox. If the installation is located in a
non-standard directory, provide it by invoking make as follows:
Most people will leave this set to 'N'.
bool "exec prefers applets"
This is an experimental option which directs applets about to
call 'exec' to try and find an applicable busybox applet before
searching the PATH. This is typically done by exec'ing
This may affect shell, find -exec, xargs and similar applets.
They will use applets even if /bin/<applet> -> busybox link
is missing (or is not a link to busybox). However, this causes
problems in chroot jails without mounted /proc and with ps/top
(command name can be shown as 'exe' for applets started this way).
string "Path to BusyBox executable"
When Busybox applets need to run other busybox applets, BusyBox
sometimes needs to exec() itself. When the /proc filesystem is
mounted, /proc/self/exe always points to the currently running
executable. If you haven't got /proc, set this to wherever you
want to run BusyBox from.
# These are auto-selected by other options
bool "Support for logging to syslog"
This option is auto-selected when you select any applet which may
send its output to syslog. You do not need to select it manually.
bool "RPC support"
This is automatically selected if any of enabled applets need it.
You do not need to select it manually.
menu 'Build Options'
bool "Build BusyBox as a static binary (no shared libs)"
If you want to build a static BusyBox binary, which does not
use or require any shared libraries, then enable this option.
This can cause BusyBox to be considerably larger, so you should
leave this option false unless you have a good reason (i.e.
your target platform does not support shared libraries, or
you are building an initrd which doesn't need anything but
Most people will leave this set to 'N'.
bool "Build shared libbusybox"
Build a shared library libbusybox.so which contains all
libraries used inside busybox.
This is an experimental feature intended to support the upcoming
"make standalone" mode. Enabling it against the one big busybox
binary serves no purpose (and increases the size). You should
almost certainly say "no" to this right now.
bool "Feature-complete libbusybox"
default n if !FEATURE_SHARED_BUSYBOX
depends on BUILD_LIBBUSYBOX
Build a libbusybox with the complete feature-set, disregarding
the actually selected config.
Normally, libbusybox will only contain the features which are
used by busybox itself. If you plan to write a separate
standalone application which uses libbusybox say 'Y'.
Note: libbusybox is GPL, not LGPL, and exports no stable API that
might act as a copyright barrier. We can and will modify the
exported function set between releases (even minor version number
changes), and happily break out-of-tree features.
Say 'N' if in doubt.
bool "Use shared libbusybox for busybox"
default y if BUILD_LIBBUSYBOX
depends on !STATIC && BUILD_LIBBUSYBOX
Use libbusybox.so also for busybox itself.
You need to have a working dynamic linker to use this variant.
bool "Build with Large File Support (for accessing files > 2 GB)"
If you want to build BusyBox with large file support, then enable
this option. This will have no effect if your kernel or your C
library lacks large file support for large files. Some of the
programs that can benefit from large file support include dd, gzip,
cp, mount, tar, and many others. If you want to access files larger
than 2 Gigabytes, enable this option. Otherwise, leave it set to 'N'.
bool "Compile all sources at once"
Normally each source-file is compiled with one invocation of
If you set this option, all sources are compiled at once.
This gives the compiler more opportunities to optimize which can
result in smaller and/or faster binaries.
Setting this option will consume alot of memory, e.g. if you
enable all applets with all features, gcc uses more than 300MB
RAM during compilation of busybox.
This option is most likely only beneficial for newer compilers
such as gcc-4.1 and above.
Say 'N' unless you know what you are doing.
menu 'Debugging Options'
bool "Build BusyBox with extra Debugging symbols"
Say Y here if you wish to examine BusyBox internals while applets are
running. This increases the size of the binary considerably, and
should only be used when doing development. If you are doing
development and want to debug BusyBox, answer Y.
Most people should answer N.
bool "Abort compilation on any warning"
Selecting this will add -Werror to gcc command line.
Most people should answer N.
# Seems to be unused
# bool "Disable compiler optimizations."
# default n
# depends on DEBUG
# The compiler's optimization of source code can eliminate and reorder
# code, resulting in an executable that's hard to understand when
# stepping through it with a debugger. This switches it off, resulting
# in a much bigger executable that more closely matches the source
prompt "Additional debugging library"
Using an additional debugging library will make BusyBox become
considerable larger and will cause it to run more slowly. You
should always leave this option disabled for production use.
This enables compiling with dmalloc ( http://dmalloc.com/ )
which is an excellent public domain mem leak and malloc problem
detector. To enable dmalloc, before running busybox you will
want to properly set your environment, for example:
The 'debug=' value is generated using the following command
dmalloc -p log-stats -p log-non-free -p log-bad-space -p log-elapsed-time \
-p check-fence -p check-heap -p check-lists -p check-blank \
-p check-funcs -p realloc-copy -p allow-free-null
This enables compiling with Electric-fence support. Electric
fence is another very useful malloc debugging library which uses
your computer's virtual memory hardware to detect illegal memory
accesses. This support will make BusyBox be considerable larger
and run slower, so you should leave this option disabled unless
you are hunting a hard to find memory problem.
bool "Enable obsolete features removed before SUSv3?"
This option will enable backwards compatibility with SuSv2,
specifically, old-style numeric options ('command -1 <file>')
will be supported in head, tail, and fold. (Note: should
affect renice too.)
menu 'Installation Options'
bool "Don't use /usr"
Disable use of /usr. Don't activate this option if you don't know
that you really want this behaviour.
prompt "Applets links"
Choose how you install applets links.
bool "as soft-links"
Install applets as soft-links to the busybox binary. This needs some
free inodes on the filesystem, but might help with filesystem
generators that can't cope with hard-links.
bool "as hard-links"
Install applets as hard-links to the busybox binary. This might count
on a filesystem with few inodes.
bool "not installed"
depends on FEATURE_INSTALLER || FEATURE_SH_STANDALONE || FEATURE_PREFER_APPLETS
Do not install applet links. Useful when using the -install feature
or a standalone shell for rescue purposes.
string "BusyBox installation prefix"
Define your directory to install BusyBox files/subdirs in.