Q:

Run adb shell on custom device

I have several connected devices via adb :
> adb devices
List of devices attached
FA5BBBJ01013    device
00c95491829ca2a1        device

When I try to run shell :
> adb shell

it gives me error :
error: more than one device and emulator

How I can start shell on custom device without disconnecting other device? 

A:

try this one
adb -s 00c95491829ca2a1 shell

From this Documentation
If multiple emulator/device instances are running, you must specify a target instance when issuing adb commands.  To do so, use the -s option in the commands.  The usage for the -s option is:
adb -s <serialNumber> <command> 

As shown, you specify the target instance for a command using its adb-assigned serial number.  You can use the devices command to obtain the serial numbers of running emulator/device instances.  For example:
adb -s emulator-5556 install helloWorld.apk

