How to set system images (path?) when creating an Android AVD?

Pay attention that android is deprecated. Use avdmanager.

First, you need to download the necessary packages. Example of downloading API 23 packages for x86 emulators:

 ./sdkmanager "system-images;android-23;google_apis;x86"

Then accept the license agreement

 ./sdkmanager --licenses

and then create your emulator

./avdmanager create avd -n test -k "system-images;android-23;google_apis;x86" -b x86 -c 100M -d 7 -f

The message

Error: Package path is not valid. Valid system image paths are:

indicates that the package could not be found - I bet the platform wasn't correctly installed .. In order to fix that problem, You can try installing it using the following commands:

android update sdk -u --filter platform-tools,android-25
sdkmanager --verbose "system-images;android-25;google_apis;x86"

and then create the avd using: avdmanager -v create avd -n x86 -k "system-images;android-25;google_apis;x86" -g "google_apis".

I hope this helps.