How to Get Serial Number or ID of Android Emulator After it Runs?

Question

If I run several emulators with -no-window option in one machine. The command "adb devices" shows:

List of devices attached
emulator-5554  device
emulator-5556  device
emulator-5558  device
...

However, according to this output, I can't tell the difference between each emulator device at all. I need to know which emulator runs on what AVD, then I can install APKs or send commands to the emulator.

How can I recognize each emulator device or get the serial number of emulator after it runs?

Answer 1

Always start the same AVD on the same ports, don't let emulator decide. Use

$ emulator -ports X,Y @avd_X

then, the serial number will be emulator-X and your avd_X will always be on ports X,Y, so you can run your commands with this serial number, like for example

$ adb -s emulator-X shell cmd

To kill the emulator run

$ adb -s emulator-X emu kill

Answer 2

There are 2 ways that I know of to perform a reverse Serial Number to AVD name lookup

The Telnet option - The Ugly Way

As pointed out in this SO answer... you can reverse lookup the AVD name for each serial number using Telnet. This is kind of weak, because all you're doing is finding an instance of the emulator launched given a particular AVD name. It doesn't uniquely identify the emulator you are wanting to work on. It also suffers from the need to use telnet and parsing out the port number for each emulator.

First get the currently running serial numbers

adb devices

then telnet to each device's port number

telnet localhost 5554

and issue the command

avd name

which will return the AVD name of that emulator.

The UUID option - The Right Way

I originally saw this done in a project called DCMTK. Generate a UUID uuidgen and set a property on the emulator at launch! My example launches an emulator to perform some compile time checks for libraries that require running code on the target to determine type information.

emulator -avd nexus19-arm -no-window -no-boot-anim -noaudio -prop emu.uuid=7a6f8701-43c2-4e16-988a-8b4992c0bf8d >/dev/null </dev/null 2>&1 &

Then when you want to find that specific instance of the emulator you just roll through all running emulators and look for that UUID.

adb -s emulator-5556 shell getprop emu.uuid

in a loop:

for SERIAL_NUMBER in `adb devices| grep emulator| cut -f1`; do 
    UUID=`adb -s ${SERIAL_NUMBER} shell getprop emu.uuid | tr -d '\r\n'`
    echo ${SERIAL_NUMBER} ${UUID}
done

Tracking the whole emulator lifecycle

1. Launch the emulator with a UUID property
2. Then kick off a loop that checks each device to be online and/or having the matching UUID
3. Once you get a match call adb -s ${SERIAL_NUMBER} wait-for-device so you know when you can talk to the emulator
4. If you need the system to be fully online check for the property sys.boot_completed
5. When you're done just kill of the emulator with adb -s ${SERIAL_NUMBER} emu kill