How to use ADB Shell when Multiple Devices are connected? Fails with "error: more than one device and emulator"
Use the -s option BEFORE the command to specify the device, for example:
adb -s 7f1c864e shellSee also http://developer.android.com/tools/help/adb.html#directingcommands
adb -d shell (or adb -e shell).
This command will help you in most of the cases, if you are too lazy to type the full ID.
From http://developer.android.com/tools/help/adb.html#commandsummary:
-d- Direct an adb command to the only attached USB device. Returns an error when more than one USB device is attached.
-e- Direct an adb command to the only running emulator. Returns an error when more than one emulator is running.
Another alternative would be to set environment variable ANDROID_SERIAL to the relevant serial, here assuming you are using Windows:
set ANDROID_SERIAL=7f1c864eecho %ANDROID_SERIAL%"7f1c864e"Then you can use adb.exe shell without any issues.