adb commad to find out if VPN tunnel is established in Android

If there is any VPN tunnel established the following command will show

Windows:
adb shell netcfg | grep tun0


Mac:
./adb shell netcfg | grep tun0


If VPN is established the result would be something like this

  tun0     UP                                  172.17.0.4/24  0x00000051 00:00:00:00:00:00

else the result would be something like this

  error: protocol fault (no status)