The Lightweight Unix Toolset - Busybox

Busybox is a useful piece of software for embedded POSIX systems. This means Busybox can run on Linux (including Android) and BSD systems. It is also a great alternative to the GNU shellutils, fileutils, etc. In general, Busybox is a light-weight form of the GNU utilities and works the same way as the various GNU and Unix commands. Busybox is a single executable file that contains multiple commands. (http://www.busybox.net/)

Busybox is free and open-source under the GPL license. The source code can be obtained from Github at http://git.busybox.net/busybox/ . Developers can remove commands at compile time to make their own smaller executable. The default executable may be around two megabytes.

collier@Nacho-Linux:~$ file `which busybox`
/bin/busybox: ELF 64-bit LSB executable, x86-64, version 1 (GNU/Linux), statically linked, for GNU/Linux 2.6.24, BuildID[sha1]=a840320c89f3534a47f7cd2afa50c5a42214decd, stripped
collier@Nacho-Linux:~$ ll `which busybox`
-rwxr-xr-x 1 root root 1931720 Aug 8 2014 /bin/busybox*

Busybox is not just used on embedded systems. It may also be used on mobile or small distros including firewalls. Busybox may also be used on high-performance systems since Busybox appears to be faster in most cases. The official website lists many Linux distros that uses Busybox (http://busybox.net/products.html).

Busybox commands can be initiated in one of two ways. Users can type "/bin/busybox ls" in a command-line. Alternately, a softlink named "ls" can link to Busybox. Busybox will see that the softlink is named "ls" and run as if "/bin/busybox ls" were executed.

Busybox supports the commands list below. Keep in mind that some specialized parameters may be missing.

• [
• [[
• acpid
• addgroup
• adduser
• adjtimex
• ar
• arp
• arping
• ash
• awk
• basename
• beep
• blkid
• brctl
• bunzip2
• bzcat
• bzip2
• cal
• cat
• catv
• chat
• chattr
• chgrp
• chmod
• chown
• chpasswd
• chpst
• chroot
• chrt
• chvt
• cksum
• clear
• cmp
• comm
• cp
• cpio
• crond
• crontab
• cryptpw
• cut
• date
• dc
• dd
• deallocvt
• delgroup
• deluser
• depmod
• devmem
• df
• dhcprelay
• diff
• dirname
• dmesg
• dnsd
• dnsdomainname
• dos2unix
• dpkg
• du
• dumpkmap
• dumpleases
• echo
• ed
• egrep
• eject
• env
• envdir
• envuidgid
• expand
• expr
• fakeidentd
• false
• fbset
• fbsplash
• fdflush
• fdformat
• fdisk
• fgrep
• find
• findfs
• flash_lock
• flash_unlock
• fold
• free
• freeramdisk
• fsck
• fsck.minix
• fsync
• ftpd
• ftpget
• ftpput
• fuser
• getopt
• getty
• grep
• gunzip
• gzip
• hd
• hdparm
• head
• hexdump
• hostid
• hostname
• httpd
• hush
• hwclock
• id
• ifconfig
• ifdown
• ifenslave
• ifplugd
• ifup
• inetd
• init
• inotifyd
• insmod
• install
• ionice
• ip
• ipaddr
• ipcalc
• ipcrm
• ipcs
• iplink
• iproute
• iprule
• iptunnel
• kbd_mode
• kill
• killall
• killall5
• klogd
• last
• length
• less
• linux32
• linux64
• linuxrc
• ln
• loadfont
• loadkmap
• logger
• login
• logname
• logread
• losetup
• lpd
• lpq
• lpr
• ls
• lsattr
• lsmod
• lzmacat
• lzop
• lzopcat
• makemime
• man
• md5sum
• mdev
• mesg
• microcom
• mkdir
• mkdosfs
• mkfifo
• mkfs.minix
• mkfs.vfat
• mknod
• mkpasswd
• mkswap
• mktemp
• modprobe
• more
• mount
• mountpoint
• mt
• mv
• nameif
• nc
• netstat
• nice
• nmeter
• nohup
• nslookup
• od
• openvt
• passwd
• patch
• pgrep
• pidof
• ping
• ping6
• pipe_progress
• pivot_root
• pkill
• popmaildir
• printenv
• printf
• ps
• pscan
• pwd
• raidautorun
• rdate
• rdev
• readlink
• readprofile
• realpath
• reformime
• renice
• reset
• resize
• rm
• rmdir
• rmmod
• route
• rpm
• rpm2cpio
• rtcwake
• run-parts
• runlevel
• runsv
• runsvdir
• rx
• script
• scriptreplay
• sed
• sendmail
• seq
• setarch
• setconsole
• setfont
• setkeycodes
• setlogcons
• setsid
• setuidgid
• sh
• sha1sum
• sha256sum
• sha512sum
• showkey
• slattach
• sleep
• softlimit
• sort
• split
• start-stop-daemon
• stat
• strings
• stty
• su
• sulogin
• sum
• sv
• svlogd
• swapoff
• swapon
• switch_root
• sync
• sysctl
• syslogd
• tac
• tail
• tar
• taskset
• tcpsvd
• tee
• telnet
• telnetd
• test
• tftp
• tftpd
• time
• timeout
• top
• touch
• tr
• traceroute
• true
• tty
• ttysize
• udhcpc
• udhcpd
• udpsvd
• umount
• uname
• uncompress
• unexpand
• uniq
• unix2dos
• unlzma
• unlzop
• unzip
• uptime
• usleep
• uudecode
• uuencode
• vconfig
• vi
• vlock
• volname
• watch
• watchdog
• wc
• wget
• which
• who
• whoami
• xargs
• yes
• zcat
• zcip

Busybox can be installed on Android systems via the PlayStore as seen at the links listed below. However, these are not the only installers for Android.

• https://play.google.com/store/apps/details?id=com.jrummy.busybox.installer&hl=en
• https://play.google.com/store/apps/details?id=stericson.busybox&hl=en

Busybox has full support for shell scripts such as "sh" and "ash". Some embedded Linux developers may wish to use MicroPerl (http://www.foo.be/docs/tpj/issues/vol5_3/tpj0503-0003.html) with Busybox as opposed to Perl.

NOTE: MicroPerl comes with the source code of the regular Perl interpreter.

Toybox (http://www.landley.net/toybox/) is a BSD-licensed alternative that may not be one-hundred percent compatible with the GNU utility alternatives.

Toolbox is an Android-specific alternative to Busybox. However, Toolbox does not come with as many commands and may not be entirely compatible or equivalent with the GNU utilities. Toolbox installs under /system/bin/. Like Busybox, Toolbox is also a single executable file (/system/bin/toolbox). The source code for Toolbox can be found at https://android.googlesource.com/platform/system/core/+/master/toolbox/ .

Further Reading

• Busybox Commands - http://www.busybox.net/downloads/BusyBox.html#commands
• Emulator - http://bellard.org/jslinux/