Summary:
========================
Basic of Unix-like systems (ROOT)
-
su, root, rooting, superuser app - what is it, why we need it
- sh, bash, user/root shell - what is bash, sh; what is user shell; what is root shell; how I can recognise it each other
- Bussybox - what is BusyBox, basic list of commands from BusyBox
Android platform tools
- adb shell - what is it, for what it is
- Android SDK - what is it, tool which provides, where to download
- Tools for work with Android, adb shell - Terminal Emulator, ADB shell from Android SDK and how to use it
Custom recovery
What is custom recovery - what custom recovery is
Tools which custom recovery provides - list of tools with description which custom recovery bringin:
- ADB as root user
- USB-MS Toggle
- Backup/Restore
- Flash ZIP from sdcard
- Wipe menu
- Partition sdcard + etx2, ext3, ext4 filesystem description
- Mounts
- Others
Is it save to install? - possible problems, why should I try it?, backup/restore of original recovery
Custom ROM
- What custom ROM is?
- Is it save to install custom ROM? - potential problems
- What I need for install?
- What can custom ROM brings - kernel, update, performance, customization, theme, ....
- what is ...
- deodexed, zipaglined, png-optimized
- JIT, HW:acceleration, VM.Heap Size, stagefright
- apps2sd + dalvik2sd
- custom kernel (recompiled, ...)
===========================================
Basic of Unix-like systems (ROOT)
su
Also
referred as substitute user - is command for changing of the account in
current terminal (usually black screen with blinking cursor). Default
account is root account. So if you insert into terminal 'su' and hit
enter, you will become root user.
root
Root
alias superuser or poweruser is special user account for system
administration. Similar to windows having its administrator account,
unix-like system have system have the root. With this user you can do
anything and if you will run command for delete whole system, unix will
just do it! No asking, no confirming. So, watch your steps!
rooting
Rooting is just enabling power of root for applications or our proposes. You can read great article about Rooting on
androidpolice.
Superuser app
After
rooting is done, you will see new app called superuser in app drawer.
This app can delegate applications to use su (root) feature. When app
ask for first use, popup window will appear asking if the application
should be allowed to use root permission.
sh, bash
is
a command-line interpreter or shell that provides a traditional user
interface for the Unix operating system and for Unix-like systems. So
simply, it is some interface, which can execute command(s), which you
have entered. Many shells exist, but in scope of android you can (as far
as I know) use only sh (standard - Bourne-shell) or bash (compiled in
BusyBox or separately on
XDA).
Both are basically same, but bash has much more future and it is
comfortable. It's too big to describe here, so if you are interested in
learning more, follow links in sources section.
user/root shell
How
do I know if I'm root or normal user? It's simple. Root's shell is
ended with # (usually it's shell looks like "bash-3.2# _") and user's
ends with $ (usually bash-3.2$ _). In terminal emulator you also can
have only [path]($|#) (for root for example "/etc # _")
BusyBox
also
called "The Swiss Army Knife of Embedded Linux" is a tool which brings
into Android basic tools known from unix system, but is much more
smaller than standard tools is. But this "packing" brings also limits in
possibilities in comparison to standard tools in unix-system (missing
special modes of tool, color output and so on). Many application use
this. For example
busybox grep (filtering of text) is needed for application called
Market enabler.
BusyBox commands
list of commands
is really wide, so it's not possible explain all, so I pickup only top
few. (hint: if you want what some command do, just search on google for
"man <command_name>" for example
man mv or enter command
here
- cd - cange directory - same like in windows. You can switch directory. example: cd /sdcard
- ls - list of files in actual directory (have few switches like for example: ls -l /sdcard/*.png (detailed listing)
- cat - print file into standart output (like more in windows) Example: cat /sdcard/data.txt
- vi - editing of file. But on limited phone keyboard (no keyboard) it is little harder Read more about vi
- cp - copy of one or more file. Example: cp /sdcard/bike.jpg /sdcard/media/bike-wallpaper.jpg
- mv - moving/rename files, Example: mv /sdcard/bike.jpg /sdcard/media/renamed-moved-bike.jpg
- rm - delete file (rm -R for recursive, or for delete whole folder), Example: rm -R /sdcard/wallpaper-bad/*
- find - search for files, Example find / -name "best-chopper-ever.avi"
- mkdir - make directory - creates directory, Example: mkdir mynewdir
- chmod - changes access of files
- less - similar like cat, but you can scroll in it and it doesn't produce any output. Example: less /sdcard/funnytext.txt
Please, take note that man pages are documentation of unix
tools. For BusyBox's tool help, just enter BusyBox <command_name>
-h.
Many time, when is BusyBox installed, are also
symbolic links created. It means, that is not necessary do BusyBox
<command>, but only <command> will be enough.
Kernel
http://en.wikipedia.org/wiki/Kernel_%28computing%29
Android platform and it's specifics
ADB
- Android Debug Bridge is a versatile tool lets you manage the state of
an emulator instance or Android-powered device. It is a client-server
program that includes three components:
- A client, which runs on your development machine. You can invoke a
client from a shell by issuing an adb command. Other Android tools such
as the ADT plugin and DDMS also create adb clients.
- A server, which runs as a background process on your development
machine. The server manages communication between the client and the adb
daemon running on an emulator or device.
- A daemon, which runs as a background process on each emulator or device instance.
Generally it can be compared with standard cmd prompt in windows
(you can write commands which will be executed locally, for example in
Terminal Emulator) or it can be just like SSH in unix-like system (you
connect to terminal through adb client (in Android SDK) and commands
will be run remotely.
Android SDK
Android
software development kit is complex set of tools for developing app on
Android. It includes fully usable emulator of Android OS on your PC,
where you can do everything. You can install/delete apps, browse web
page in embedded web browser, play games or make your own application in
Eclipse (widely used IDE for development). Of course, with emulator you
can use also GPS or camera. Emulated android phone is just like
"normal" phone.
Android SDK tools
Tools for work with Android adb shell
You have two ways ho to connect into ADB service - locally and remotely.
Locally - for local access you will need some application which can connect to local adb shell.
- Terminal Emulator (free) - probably most commonly used app from market, which works and looks like standard unix shell.
- ConnectBot (free) - same as Terminal Emulator, but it can be also used for connecting via SSH or telnet
- Remotelly- For remote connection you need phone configuration adjustment:
Home desktop -> [menu button] -> Settings -> Applications -> Development -> USB debugging [ON].
Also you need connect your phone via USB (or finds on market some
widget/app, witch enable using ADB also via wi-fi)
adb tool from Android SDK
After
download Android SDK, extract archive somewhere (in example I extracted it in c:/AndroidSDK). Then follow instruction on
developer.android.com
for installation of SDK Platform-tools (contains adb). After
installation click on start menu and in Run... (in Windows7 in search
bar) enter 'cmd' and press Ok or [enter]. Then write in cmd line:
cd c:\AndroidSDK\android-sdk-windows\tools [enter]
now
you can enter following command to connect to phone's adb shell if you
don't have more connected device (virtual or real-one)
adb shell
If you have more then one, you need explicitly say which one should be used for connection. So
list connected devices with
adb devices
which shows you serial number of connected devices. Than use
adb -s <serial-number> shell
Custom recovery
What is custom recovery
Recovery
is image (binary data) stored in internal memory. This image contains
something like "program" maybe better say "tool", which can boot-up
independently on Android system. In other words, when this tool is
running (booted up), than Android system is not. This tool is part of
phone system, and in PC terminology recovery can by compared to BIOS
with some added features. This recovery state can be reached on all
phone, but if you don't have custom recovery, it will do offten, but not
always so-called HW reset and automatically restart itself into
standard boot mode. So what is difference between original recovery and
custom recovery? Custom recovery didn't call master reset after start
and also didn't restart itself.
Tools which custom recovery provides
Let's go check what custom recovery brings.
ADB as root user
USB-MS Toggle :mounts sdcard as mass storage
It
just mounts your phone as USB-mass storage (USB disk) so in PC you will
see new disk where you can see folders based on mountes (lower) and
were you can upload what you want.
Backup/Restore:
Absolutely
GREAT feature. With NAND you can do 1:1 copy (image) of your actual
system (phone's memory). It means, that you didn't backup only SMS,
contacts or apps, but whole system with all configuration,
customization, wallpapers, system's tweaks... just everything - it
creates image of whole phone system. This image will be written to your
SD card which you are then free to copy around and back up on your
computer.
What it means? You find custom ROM which
looks awsome so you create NAND backup and install new ROM, but after
few hour/days... you know, ROM before was better. So you boot into
recovery, use NAND restore of your old ROM backup and .... woala you
have your system just like before backup - as if nothing had happened.
For about 2 minutes!! It sounds great, isn't? But one, little problem
exist. You can not use for restore only some part of backup. You have to
restore all, or nothing.
Flash Zip From Sdcard
This
tool is designed for install of custom ROM or for tweaks. If you have
instruction to install via custom recovery, and file have .zip extension
than you should use this menu. Never unzip file, because file contain
meta-information about itself with some validate-checks so if you edit
it, or unpack and pack back, it shouldn't work. And of course you can't
select *.zip file if it doesn't exist because you unpack it, also you
have not to rename it to update.zip, you can just select file to update
in list of .zip files.
Wipe
Wipe data/factory reset: wipes data & cache
wipe of users data (contacts, apps, configuration, ...) and cache (caches of applications)
Wipe cache
wipe cache only
Wipe Dalvik cache : Wipes Dalvik cache in all possible locations if moved by apps2sd
wipe of
Dalvik cache?
Wipe SD:ext : Wipes Apps2sd ext partition
if you used Partition SDcard option, you can wipe it here
Wipe Battery Stats
If you think, that your battery life is too short, you can try delete battery stats. Than let phone fully charge. (
more)
Partition Sdcard:
will create ext2 partition (you will be asked for size of ext2 and cache) Than you can use this space as part of system memory.
- ext2 - file system for the Linux kernel (no journal, fast but not recovery of I/O error)
- ext3 - file system for the Linux kernel (journal, slower than ext2 because of journal, but provides recovery on I/O error)
- ext4 - file system for the Linux kernel (journal, enhanced version of ext3)
Mounts:
Mounting of filesystem parts
Install or not to install?
- Where can problems arise?
- loss of warranty - service have much more advanced software and
hardware and they can check what problem caused - make dump of memory
and so on. They mostly doesn’t do, but they can.
- bricking of phone - if something goes wrong, then phone may not start at all
- deletion of all data if installation fails - if old recovery remains, than hw reset will be performed
- custom recovery doesn't work at all - incompatible devices
Why to try?
- NAND backup/restore - the most useful tool ever
- you can install custom ROM
- high count of successful flashing of custom recovery
- for now (what I read on forum), when you had said that you brick
your phone by standard manufacturer tool, your warranty repair would be
probably approved
What is custom ROM?
Custom ROM is every
somehow changed manufacturer's ROM or ROM compiled from source code of
Android. "Change/s" can starts with adding/removing default application
and can extend to kernels, cpu over/under-clocking, enable/disable
features (ROOT, HW acceleration, ...), themes (frameworks, color, ...),
keyboards and many other features.
Custom ROM is mostly
distributed like signed ZIP package with included installation script
for custom recovery. This ZIP is flashed via
custom recovery tool.
Is it save to install custom ROM?
Yes,
it is. May be I can say, that installation of custom ROM is almost
mandatory, because it cost you only few minute if you will not be
satisfied - you can just restore your old ROM from NAND backup, if you
will be satisfied, you can keep it. And yes, you can also use backup
tools like for example Astro for backup of your apps or Titanium Backup
backup everything (SMS, call list, preferences, APNs, ...) and restore
this in your new ROM (NOTE: In this case it's strongly recommended that
both ROM should have same or very similar source/base ROM).
So, it is really simple:
- Do NAND backup
- Try new ROM
- Keep new, or restore old one.
What I need for install?
- Rooted phone
- Installed custom recovery
- Signed .ZIP file of ROM compatible with recovery
- RECOMMENDED: NAND backup of your actual ROM
What does custom ROM bring
Custom ROM brings almost every feature you can image.
ex:
- optimization for maximal power (games), long battery life, calling, texting, playing videos,...
- awsome look - changed icons, colors, animations, wallpapers, menu, ....
- simple work - feature that will short some work (add restart button, reorganized menu, shorts, gestures, ...)
- allow tweaking - overclok/underclok your device, ROOT, ....
- and many other
It's really not possible describe here every possibility what you can do/get with custom ROM.
what is ...
deodexed -
needed for using themes. If you want replace/change some file in system
(change theme) you need deodex file which you want change. In most
cases it's going on services.jar which contains definition of colour for
clock for example.
APKs zipaligned - optimization of APK archive, so it takes less memory and is much faster.
png-optimized - png files takes less memory, are loads faster
JIT
- just-in-time compilation also known as dynamic translation, is a
method to improve the runtime performance of computer programs, but it
takes some time to convert into it on start.
HW:acceleration - using of HW acceleration for rendering GUI. Little increase battery consumption.
VM.Heap Size - maximum memory an application can consume
stagefright - In Android 2.2 new media framework that supports local file playback and HTTP progressive streaming
Apps2SD
- (mostly DarkTremor's a2sd) If you create ext partition on your SD
card, you can mount it like internal memory (you will have more space on
phone memory) and move app on SD.
Dalvik2SD - move of Dalvik into SDcard (saves space)
custom kernel - compiled standard unix kernel (can bring support for features like support ext4 for example)
Links/sources
----------------------------------------------------
su (Unix);
wikipedia.org
Superuser;
wikipedia.org
Bourne shell (sh);
wikipedia.org
Bourne-Again shell (bash);
wikipedia.org
BusyBox;
benno.id.au;
BusyBox.net
Kernel;
wikipedia.org
How to increase battery life;
androidforums.com
Comparison of file systems;
wikipedia.org
ZeroXtreme's filesystem answer (thanks);
forum.xda-developers.com
ADB;
android-dls.com;
developer.android.com
Android SDK;
wiki.androidforum.cz [CZ]
Basic adb/shell commands for noobs;
forum.xda-developers.com
15 Useful Android Terminal (ADB Shell) Commands;
gadgetsdna.com
P500 custom ROM list;
forum.xda-developers.com
What's Deodex and Odex?;
forum.xda-developers.com
What Is Zipalign In Android
www.addictivetips.com
PNG compress;
http://www.gotow.net/creative/wordpress/?p=79
Just-in-time compilation;
wikipedia.org
VM Heap size;
forum.cyanogenmod.com
Stagefright;
developer.android.com
