Refer to the document http://developer.android.com/tools/device.html#setting-up:
- Make sure enable something like Developer options, USB debugging...on your device.
- As root, create/modify the file /etc/udev/rules.d/51-android.rules in your Ubuntu system.
- Add a line in the file
SUBSYSTEM=="usb", ATTR{idVendor}=="xxxx", MODE="0666", GROUP="plugdev"
where xxxx is the vendor id of your device. You can use the Linux command lsusb to get the vendor id of your device, refer 2:05 of the below video to know how to.
- Run the command to execute it:
$ chmod a+r /etc/udev/rules.d/51-android.rules
After setup /etc/udev/rules.d/51-android.rules, you can download and run your apps on real devices.