Use the mksdcard tool to create a FAT32 disk image that you can load into
    emulators running different Android Virtual Devices (AVDs) to simulate the presence
    of the same SD card in multiple devices.
  
    The mksdcard tool provided in the Android SDK Tools package
    is located in android-sdk/emulator/mksdcard.
  
    If you don't need a disk image that can be shared
    among multiple virtual devices, you don't need to use the mksdcard command.
    By default, the emulator uses the default image that is generated by and stored with the
    active AVD instead.
  
Usage
    To use the mksdcard tool, use the following command:
mksdcard -l label size file
Options
The following table describes the command-line options of mksdcard:
| Option | Description | 
|---|---|
| -l label | A volume label for the disk image to create | 
| size | An integer that specifies the size of the disk image to create. If size is a simple integer, it specifies the size in bytes. You can also
      specify the size in kilobytes, megabytes, or gigabytes by appending K, M, or G
        to size. For example,  | 
| file | The path/filename of the disk image to create relative to the current working directory. | 
Example
  Create the mySdCardFile.img disk image:
mksdcard -l mySdCard 1024M mySdCardFile.img
  Start two emulators with different AVDs. Use the -sdcard flag to specify the name
  and path of the disk image you created:
emulator -avd Pixel_API_25 -sdcard mySdCardFile.img emulator -avd NEXUS_6_API_25 -sdcard mySdCardFile.img
emulator command and its options,
  see Start the emulator from the command line.
  
  
    