有用過 Android adb shell 的人應該都知道這個 shell 的功能實在是食之無味棄之可惜的雞肋，一些常用的 linux command 幾乎都不支援，所以今天要介紹 busybox 這個工具，它的支援相當豐富，以下是執行的畫面：
$ busybox
BusyBox v1.16.0 (2010-01-27 20:00:00 CET) multi-call binary.
Copyright (C) 1998-2009 Erik Andersen, Rob Landley, Denys Vlasenko
and others. Licensed under GPLv2.
See source distribution for full notice.
Usage: busybox [function] [arguments]...
or: function [arguments]...
BusyBox is a multi-call binary that combines many common Unix
utilities into a single executable. Most people will create a
link to busybox for each function they wish to use and BusyBox
will act like whatever it was invoked as.
Currently defined functions:
[, [[, 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, cttyhack,
cut, date, dc, dd, deallocvt, delgroup, deluser, depmod, devmem, df,
dhcprelay, diff, dirname, dmesg, dnsd, dnsdomainname, dos2unix, du,
dumpkmap, dumpleases, echo, ed, egrep, eject, env, envdir, envuidgid,
ether-wake, expand, expr, fakeidentd, false, fbset, fbsplash, fdflush,
fdformat, fdisk, fgrep, find, findfs, flash_eraseall, flash_lock,
flash_unlock, flashcp, fold, free, freeramdisk, fsck, fsck.minix,
fsync, ftpd, ftpget, ftpput, fuser, getopt, getty, grep, gunzip, gzip,
halt, 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, lspci, lsusb, lzmacat, lzop, lzopcat, makedevs,
makemime, man, md5sum, mdev, mesg, microcom, mkdir, mkdosfs, mke2fs,
mkfifo, mkfs.ext2, mkfs.minix, mkfs.vfat, mknod, mkpasswd, mkswap,
mktemp, modprobe, more, mount, mountpoint, msh, mt, mv, nameif, nc,
netstat, nice, nmeter, nohup, nslookup, ntpd, od, openvt, passwd,
patch, pgrep, pidof, ping, ping6, pipe_progress, pivot_root, pkill,
popmaildir, poweroff, printenv, printf, ps, pscan, pwd, raidautorun,
rdate, rdev, readahead, readlink, readprofile, realpath, reboot,
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, traceroute6, true, tty, ttysize,
tunctl, tune2fs, udhcpc, udhcpd, udpsvd, umount, uname, uncompress,
unexpand, uniq, unix2dos, unlzma, unlzop, unzip, uptime, usleep,
uudecode, uuencode, vconfig, vi, vlock, volname, wall, watch, watchdog,
wc, wget, which, who, whoami, xargs, yes, zcat, zcip
網路上已經有人幫忙把 busybox comile 成 android 可以用的 binary 檔了，有需要的人可以到
這裡下載。
安裝 busybox 的步驟如下：
1. 建立安裝的目錄
adb shell mkdir /data/busybox
2. 複製 busybox 的 binary 檔到前一個步驟所建立的目錄：
adb push busybox /data/busybox/busybox
3. 開始安裝 busybox
adb shell
cd /data/busybox
./busybox --install.
然後你可以檢查 /data/busybox 目錄，裡面應該有許多links.
但是預設的路徑並沒有被指定到 /data/busybox 為了讓用起來方便一點，可以修改 init.rc 多加進去 busybox 的安裝路徑，但如果是在 emulator 上 run 那就要去修改 ramdisk.img 才能達到一勞永逸的效果，否則每次開啟 emulator 後 init.rc 會被覆蓋掉。
修改 ramdisk.img 的步驟：
2.6內核開始，initrd.img採用cpio壓縮，ramdisk.img也一樣，使用gunzip解壓縮，然後再使用 cpio解包。
1. 將 ramdisk.img 從 android sdk 的 platroms\android-xx 目錄下複製到 linux 的作業環境其他目錄(如果已經在 linux 下則此一步驟省略)
2. 名稱改為 ramdisk.img.gz 並用 gunzip 解壓
mv ramdisk.img ramdisk.img.gz
gunzip ramdisk.img.gz
3. 新建一個文件夾 ramdisk 並進入此目錄後用 cpio 解開
mkdir ramdisk
cd ramdisk
cpio -i -F ../ramdisk.img
此時現在目錄已經是解開後的 ramdisk 檔案目錄了
4. 修改 init.rc 在 PATH 中加上 /data/busybox 路徑
## Global environment setup
##
env {
#其中, /data/busybox 為busybox安裝路徑，bash也是放在其中
PATH /data/busybox:/sbin:/system/sbin:/system/bin
...
}
5. 重新打包 ramdisk
find . | cpio -o -H newc -O ../new_ramdisk.img
gzip ../new_ramdisk.img
6. 把 new_ramdisk.img.gz 改成 ramdisk.img 並複製到 emulator 原來放置 ramdisk.img 的目錄覆蓋掉。大功告成...^^
