Add a README.md about our shell and utilities.

Android's shell and utilities

=============================

Since IceCreamSandwich Android has used

[mksh](https://www.mirbsd.org/mksh.htm) as its shell. Before then it used

[ash](https://en.wikipedia.org/wiki/Almquist_shell) (which actually

remained in the tree up to and including KitKat).

Initially Android had a very limited command-line provided by its

own "toolbox" binary. These days almost everything is supplied by

[toybox](http://landley.net/toybox/) instead.

We started moving a few of the more important tools to full

BSD implementations in JellyBean before we started in earnest in

Lollipop. Lollipop was a major break with the past in many ways (LP64

support and the switch to ART both having lots of knock-on effects around

the system), so although this was the beginning of the end of toolbox it

(a) didn't stand out given all the other systems-level changes and (b)

in Marshmallow we changed direction and started the move to toybox.

The lists below show what tools were provided and where they came from in

each release starting with Gingerbread. This doesn't tell the full story,

because the toolbox implementations did have bugs fixed and options added

over the years. Gingerbread's rm, for example, supported `-r`/`-R` but not

`-f`. But this gives you an idea of what was available in any given release,

and how usable it was likely to be.

Android 2.3 (Gingerbread)

-------------------------

BSD: cat dd newfs\_msdos

toolbox: chmod chown cmp date df dmesg getevent getprop hd id ifconfig

iftop insmod ioctl ionice kill ln log ls lsmod lsof mkdir mount mv

nandread netstat notify printenv ps reboot renice rm rmdir rmmod route

schedtop sendevent setconsole setprop sleep smd start stop sync top

umount uptime vmstat watchprops wipe

Android 4.0 (IceCreamSandwich)

------------------------------

BSD: cat dd newfs\_msdos

toolbox: chmod chown cmp date df dmesg getevent getprop hd id ifconfig

iftop insmod ioctl ionice kill ln log ls lsmod lsof mkdir mount mv

nandread netstat notify printenv ps reboot renice rm rmdir rmmod route

schedtop sendevent setconsole setprop sleep smd start stop sync top

touch umount uptime vmstat watchprops wipe

Android 4.1-4.3 (JellyBean)

---------------------------

BSD: cat cp dd du grep newfs\_msdos

toolbox: chcon chmod chown clear cmp date df dmesg getenforce getevent

getprop getsebool hd id ifconfig iftop insmod ioctl ionice kill ln

load\_policy log ls lsmod lsof md5 mkdir mount mv nandread netstat notify

printenv ps reboot renice restorecon rm rmdir rmmod route runcon schedtop

sendevent setconsole setenforce setprop setsebool sleep smd start stop

sync top touch umount uptime vmstat watchprops wipe

Android 4.4 (KitKat)

--------------------

BSD: cat cp dd du grep newfs\_msdos

toolbox: chcon chmod chown clear cmp date df dmesg getenforce getevent

getprop getsebool hd id ifconfig iftop insmod ioctl ionice kill ln

load\_policy log ls lsmod lsof md5 mkdir mkswap mount mv nandread netstat

notify printenv ps readlink renice restorecon rm rmdir rmmod route runcon

schedtop sendevent setconsole setenforce setprop setsebool sleep smd start

stop swapoff swapon sync top touch umount uptime vmstat watchprops wipe

Android 5.0 (Lollipop)

----------------------

BSD: cat chown cp dd du grep kill ln mv printenv rm rmdir sleep sync

toolbox: chcon chmod clear cmp date df dmesg getenforce getevent getprop

getsebool hd id ifconfig iftop insmod ioctl ionice load\_policy log ls

lsmod lsof md5 mkdir mknod mkswap mount nandread netstat newfs\_msdos

nohup notify ps readlink renice restorecon rmmod route runcon schedtop

sendevent setenforce setprop setsebool smd start stop swapoff swapon

top touch umount uptime vmstat watchprops wipe

Android 6.0 (Marshmallow)

-------------------------

BSD: dd du grep

toolbox: df getevent iftop ioctl ionice log ls lsof mount nandread

newfs\_msdos ps prlimit renice sendevent start stop top uptime watchprops

toybox: acpi basename blockdev bzcat cal cat chcon chgrp chmod chown

chroot cksum clear comm cmp cp cpio cut date dirname dmesg dos2unix echo

env expand expr fallocate false find free getenforce getprop groups

head hostname hwclock id ifconfig inotifyd insmod kill load\_policy ln

logname losetup lsmod lsusb md5sum mkdir mknod mkswap mktemp modinfo

more mountpoint mv netstat nice nl nohup od paste patch pgrep pidof

pkill pmap printenv printf pwd readlink realpath restorecon rm rmdir

rmmod route runcon sed seq setenforce setprop setsid sha1sum sleep sort

split stat strings swapoff swapon sync sysctl tac tail tar taskset tee

time timeout touch tr true truncate umount uname uniq unix2dos usleep

vmstat wc which whoami xargs yes

Android 7.0 (Nougat)

--------------------

BSD: dd grep

toolbox: getevent iftop ioctl log nandread newfs\_msdos ps prlimit

sendevent start stop top

toybox: acpi base64 basename blockdev bzcat cal cat chcon chgrp chmod

chown chroot cksum clear comm cmp cp cpio cut date df dirname dmesg

dos2unix du echo env expand expr fallocate false find flock free

getenforce getprop groups head hostname hwclock id ifconfig inotifyd

insmod ionice iorenice kill killall load\_policy ln logname losetup ls

lsmod lsof lsusb md5sum mkdir mknod mkswap mktemp modinfo more mount

mountpoint mv netstat nice nl nohup od paste patch pgrep pidof pkill

pmap printenv printf pwd readlink realpath renice restorecon rm rmdir

rmmod route runcon sed seq setenforce setprop setsid sha1sum sleep sort

split stat strings swapoff swapon sync sysctl tac tail tar taskset tee

time timeout touch tr true truncate tty ulimit umount uname uniq unix2dos

uptime usleep vmstat wc which whoami xargs xxd yes

Current AOSP

------------

BSD: dd grep

bzip2: bzcat bzip2 bunzip2

toolbox: getevent gzip newfs\_msdos gunzip zcat

toybox: acpi base64 basename blockdev cal cat chcon chgrp chmod chown

chroot chrt cksum clear cmp comm cp cpio cut date df diff dirname dmesg

dos2unix du echo env expand expr fallocate false file find flock free

getenforce getprop groups head hostname hwclock id ifconfig inotifyd

insmod ionice iorenice kill killall ln load\_policy log logname losetup

ls lsmod lsof lsusb md5sum microcom mkdir mknod mkswap mktemp modinfo

modprobe more mount mountpoint mv netstat nice nl nohup od paste patch

pgrep pidof pkill pmap printenv printf ps pwd readlink realpath renice

restorecon rm rmdir rmmod runcon sed sendevent seq setenforce setprop

setsid sha1sum sha224sum sha256sum sha384sum sha512sum sleep sort split

start stat stop strings swapoff swapon sync sysctl tac tail tar taskset

tee time timeout top touch tr true truncate tty ulimit umount uname uniq

unix2dos uptime usleep uudecode uuencode vmstat wc which whoami xargs

xxd yes