How to root Android Jelly Bean from terminal inside Android I have installed the Android Terminal Emulator inside Android Jelly Bean (4.2.2).
The device being used is http://www.laptopmag.com/reviews/mini-pcs/rk3188-android-mini-pc.
This device has problems connecting over adb to my computer. Am also unable to enter the recovery mode/download mode on this device. Hence I cannot use any of the standard tools for rooting my device.
However, I have been able to install the Android Terminal Emulator app inside Android Jelly Bean. Is it possible to root my device from the Android Terminal Emulator. Please guide me.

Is it possible to root a device via some custom system update file put in an SD? Even this could work out for me.
No. On a few devices' stock ROMs it's possible to use a security vulnerability in a driver or the kernel to root the device from the device itself, but they generally require a specific app to work (such as Framaroot for the devices and ROMs it supports). AFAIK, there isn't a single device you can exploit this way to get root from the command-line. On devices without such a vulnerability, you can only unlock the bootloader from fastboot, which requires you to be in fastboot mode, or some equivalent vendor-specific tool.