adb-devices

List all connected devices

$ adb devices

$ adb devices -l

adb devices [-l]

adb devices lists all Android devices currently connected to the computer, whether via USB or wireless connection. The output shows device serial numbers and their connection states.
Device states include: device (connected and ready), offline (not responding), unauthorized (USB debugging not authorized), no permissions (Linux udev rules issue), and bootloader (in fastboot mode).

-l

Long output format showing additional device information (product, model, device, transport_id)

Devices showing "unauthorized" require you to accept the RSA key prompt on the device. "No permissions" errors on Linux usually require udev rules for your device. Emulators appear as emulator-5554 or similar.

The adb devices command has been part of adb since its initial release with the Android SDK in 2008. The -l flag for extended information was added later to help distinguish between multiple devices of the same model.

adb(1), adb-connect(1), fastboot(1)