How to configure Android Emulator once SDK is installed

Issue

I am trying to get the Android emulator up and running on my 64-bit Ubuntu 12.04 distro. First, I had to install ia32-libs to get around some earlier issues that I had encountered on previous (failed) attempts.

I then downloaded and installed the 64-bit linux distro. I navigated to the android application (SDK Manager) on the command line, and ran it. I downloaded Android Tools and the latest flavor of the Android OS.

I would now like to run emulator, but when I do, I get the following error:

myUser@myMachine:~/android-sdk/21.1/android-sdk-linux/tools$ ./emulator

emulator: ERROR: You did not specify a virtual device name, and the system
directory could not be found.

If you are an Android SDK user, please use '@<name>' or '-avd <name>'
to start a given virtual device (see -help-avd for details).

Otherwise, follow the instructions in -help-disk-images to start the emulator

When I run ./emulator -help-disk-images I get output that includes the following:

kernel-qemu      the emulator-specific Linux kernel image
ramdisk.img      the ramdisk image used to boot the system
system.img       the *initial* system image
userdata.img     the *initial* data partition image

It will also use the following writable image files:

userdata-qemu.img  the persistent data partition image
system-qemu.img    an *optional* persistent system image
cache.img          an *optional* cache partition image
sdcard.img         an *optional* SD Card partition image

snapshots.img      an *optional* state snapshots image

If you're neither using the SDK or the Android build system, you
can still run the emulator by explicitely providing the paths to
*all* required disk images through a combination of the following
options: -sysdir, -datadir, -kernel, -ramdisk, -system, -data, -cache
-sdcard and -snapstorage.

This is very confusing. I've seen YouTube examples of people using the emulator with nothing more than ./emulator -datadir=/some/path.

So I ask:

• What's the difference between running the emulator via the SDK, the "Android build system" (???), and via the terminal like what I'm attempting here?
• Why is it possible in some cases to run the emulator via ./emulator -datadir=/some/path, but the output in this 2nd window seems to require 4 - 8 command line arguments?
• At what point do I fire up the AVD Manager and set up my machine?

Thanks in advance!

Solution

You must create an AVD configuration before launching the emulator:

android create avd -n <name> -t <targetID> [-<option> <value>] ... 

http://developer.android.com/tools/devices/managing-avds-cmdline.html#AVDCmdLine

then you're ready to launch it

emulator -avd <avd_name> [<options>]

http://developer.android.com/tools/devices/emulator.html#starting

Answered By - Diogo Bento