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What is Android?

Android is an open-source operating system for mobile devices. It is basically a java virtual machine running on a Linux-based kernel.



What is the Android SDK and do I need it?

SDK stands for "software development kit. Do you need it? If you are developing, then yes (but then you probably would be reading this thread now would you... ). If you are not developing, then no, you do NOT need to install it. It is just a waste of space. The only files you need (to interface with your PC) that comes from the SDK are the fastboot and adb files, and they can be found here for Windows, Linux, and MacOS.



What is a command prompt?

A command prompt in Windows (or terminal in Linux/MacOS) is a command line window in which you can enter commands. To open a command prompt in Windows, you can hold the shift key and right click in the directory in which you want your command prompt open. Or, in a Windows Explorer window you can go to File-><name-of-window>->Open command window here.



What is a bootloader?

Without getting into too many technicalities, the bootloader is essentially the program that gets loaded first when starting your device, and it is responsible for booting the Android kernel. Think of the bootloader as the BIOS of a computer.



What is “root”?

Root essentially means that you have root (or superuser) access to the file system on Android. It is similar to being “administrator” on a Windows PC. It has nothing to do with your device or the bootloader, it has to do with the Android OS (i.e., you cannot “root” your device – you root the Andoid build that you are running). To have root, you need to be booted into the Android OS that you have rooted. If you are in fastboot mode, root is irrelevant.



How do I get “root”?

If you are booted into a custom recovery (recoveries will be covered later), root is enabled by default. If you want root while booted into Android, you will need to place two files on your system partition: an “su” binary which grants root access, and a superuser app that manages that access. The two that are available are ChainsDD’s Superuser and Chainfire’s SuperSU. Usually these files are packaged up in a zip file that is flashable using a custom recovery, but they can be flashed manually using ADB. Both of these methods will be described below.



If I unlock my bootloader, is that the same as root?

No, as was mentioned above, unlocking the bootloader allows you to (among a few other things) flash images easily to the device when not booted into the Android OS. Root allows you access to manipulate the files WITHIN the Android OS.



If I unlock my bootloader, does that mean that I have to root?

No.



If I unlock my bootloader, do I have to flash a custom ROM?

No.



Do I need to root to flash a ROM?

No.



What is a ROM?

A ROM is slang for an mobile OS build.



What is the difference between a stock ROM and a custom ROM?

A stock ROM is a ROM that is either built by Google (like any yakju/takju/mysid build) or built by Samsung (like all the yakju** variants and mysidpr) and is signed by Google’s (or Samsung’s) platform keys. Everything else is a custom ROM.



What is this AOSP I keep hearing about?

AOSP stands for Android Open Source Project, and is a repository for the source code for Android. You can build your own ROM from AOSP. Details can be found on http://source.android.com/



What is fastboot?

Fastboot can refer to three things: the actual interface between your PC and phone; the fastboot.exe file; or the “mode” of your device. For you to be able to use fastboot commands: your device has to be booted in fastboot mode, the fastboot driver for your PC needs to be installed, and the fastboot.exe file needs to be on your PC.



What are the fastboot commands?

The list of fastboot commands can be seen by typing “fastboot” (without the quotes) in a command prompt opened in the directory where you fastboot.exe file is located. See below.





Code: fastboot usage: fastboot [ <option> ] <command> commands: update <filename> reflash device from update.zip flashall flash boot + recovery + system flash <partition> [ <filename> ] write a file to a flash partition erase <partition> erase a flash partition format <partition> format a flash partition getvar <variable> display a bootloader variable boot <kernel> [ <ramdisk> ] download and boot kernel flash:raw boot <kernel> [ <ramdisk> ] create bootimage and flash it devices list all connected devices continue continue with autoboot reboot reboot device normally reboot-bootloader reboot device into bootloader help show this help message options: -w erase userdata and cache -s <serial number> specify device serial number -p <product> specify product name -c <cmdline> override kernel commandline -i <vendor id> specify a custom USB vendor id -b <base_addr> specify a custom kernel base address -n <page size> specify the nand page size. default: 2048

Code: Android Debug Bridge version 1.0.29 -d - directs command to the only connected USB device returns an error if more than one USB device is present. -e - directs command to the only running emulator. returns an error if more than one emulator is running. -s <serial number> - directs command to the USB device or emulator with the given serial number. Overrides ANDROID_SERIAL environment variable. -p <product name or path> - simple product name like 'sooner', or a relative/absolute path to a product out directory like 'out/target/product/sooner'. If -p is not specified, the ANDROID_PRODUCT_OUT environment variable is used, which must be an absolute path. devices - list all connected devices connect <host>[:<port>] - connect to a device via TCP/IP Port 5555 is used by default if no port number is specified. disconnect [<host>[:<port>]] - disconnect from a TCP/IP device. Port 5555 is used by default if no port number is specified. Using this command with no additional arguments will disconnect from all connected TCP/IP devices. device commands: adb push <local> <remote> - copy file/dir to device adb pull <remote> [<local>] - copy file/dir from device adb sync [ <directory> ] - copy host->device only if changed (-l means list but don't copy) (see 'adb help all') adb shell - run remote shell interactively adb shell <command> - run remote shell command adb emu <command> - run emulator console command adb logcat [ <filter-spec> ] - View device log adb forward <local> <remote> - forward socket connections forward specs are one of: tcp:<port> localabstract:<unix domain socket name> localreserved:<unix domain socket name> localfilesystem:<unix domain socket name> dev:<character device name> jdwp:<process pid> (remote only) adb jdwp - list PIDs of processes hosting a JDWP transport adb install [-l] [-r] [-s] <file> - push this package file to the device and install it ('-l' means forward-lock the app) ('-r' means reinstall the app, keeping its data) ('-s' means install on SD card instead of internal storage) adb uninstall [-k] <package> - remove this app package from the device ('-k' means keep the data and cache directories) adb bugreport - return all information from the device that should be included in a bug report. adb backup [-f <file>] [-apk|-noapk] [-shared|-noshared] [-all] [-system|-nosystem] [<packages...>] - write an archive of the device's data to <file>. If no -f option is supplied then the data is written to "backup.ab" in the current directory. (-apk|-noapk enable/disable backup of the .apks themselves in the archive; the default is noapk.) (-shared|-noshared enable/disable backup of the device's shared storage / SD card contents; the default is noshared.) (-all means to back up all installed applications) (-system|-nosystem toggles whether -all automatically includes system applications; the default is to include system apps) (<packages...> is the list of applications to be backed up. If the -all or -shared flags are passed, then the package list is optional. Applications explicitly given on the command line will be included even if -nosystem would ordinarily cause them to be omitted.) adb restore <file> - restore device contents from the <file> backup archive adb help - show this help message adb version - show version num scripting: adb wait-for-device - block until device is online adb start-server - ensure that there is a server running adb kill-server - kill the server if it is running adb get-state - prints: offline | bootloader | device adb get-serialno - prints: <serial-number> adb status-window - continuously print device status for a specified device adb remount - remounts the /system partition on the device read-write adb reboot [bootloader|recovery] - reboots the device, optionally into the bootloader or recovery program adb reboot-bootloader - reboots the device into the bootloader adb root - restarts the adbd daemon with root permissions adb usb - restarts the adbd daemon listening on USB adb tcpip <port> - restarts the adbd daemon listening on TCP on the specified port networking: adb ppp <tty> [parameters] - Run PPP over USB. Note: you should not automatically start a PPP connection. <tty> refers to the tty for PPP stream. Eg. dev:/dev/omap_csmi_tty1 [parameters] - Eg. defaultroute debug dump local notty usepeerdns adb sync notes: adb sync [ <directory> ] <localdir> can be interpreted in several ways: - If <directory> is not specified, both /system and /data partitions will be updated. - If it is "system" or "data", only the corresponding partition is updated.

ADB can refer to two things: the actual interface between your PC and phone, or the adb files (the .exe and two .dll files for Windows). For you to be able to use adb commands: the adb driver needs to be installed on your PC, the adb files need to be on your PC, and your device has to be booted either in recovery mode or booted normally into Android. Additionally, USB debugging needs to be enabled if booted into Android.The list of ADB commands can be seen by typing “adb” (without the quotes) in a command prompt opened in the directory where your adb.exe file is located. See below.In order for a device to have access to files, the partition on which those files reside needs to be “mounted”. If you are in recovery, you can easily do this by going to the mounts menu and mounting the appropriate partition. If you are booted in Android, you will need to mount the partition yourself. The /sdcard folder is already mounted by default, however.In recovery: go to the mount menu and mount /systemIn Android, on your device: you need root, and a file explorer with root accessIn Android, connected via ADB (root required): you need to type the following command in a command prompt:adb shellsumount -o remount,rw -t ext4 /dev/block/mmcblk0p1 /systemTo explain this a bit:-o remount,rw <== this remounts a partition that is already mounted (as read-only), as read-write-t ext4 <== this specifies to mount it as ext4/dev/block/mmcblk0p1 <== this is the system partition/system <== this is what you are mounting it asRecovery is like a mini OS, which allows you to perform various functions, usually related to flashing files to your device, or updating files, or backing things up, etc. The stock image has a recovery included, but its functionality is very limited. There are a number of custom recoveries available. Most popular are TWRP and CWMEverything is the result of Googling each term.