How to use adb shell when multiple devices are connected ?

Android adb command for host, provides a command line option if you want to connect to one specific device using serial number, when you have more than 1 mobile/device is connected over USB or if abd is connected over network.

The option for adb is ” -s ” which directs adb command to the device or emulator with the given serial number or qualifier. Overrides ANDROID_SERIAL environment variable.

Check the serial number of the device you want to connect to,

 $ adb devices 
List of devices attached
B2NGAA8831702707	device1
A4NTXY6734562309        device2

Now, lets say if we want to connect to device1, then use below command,

 $ adb -s B2NGAA8831702707 shell 

Above command should connect to first device.