How to install app from command line (terminal)? How to install app from command line (terminal)? 

I would like to start a terminal window and do the apk installation from command line (shell script)

EDIT1: within the phone. 
Also is it possible to install from Google Play from URL, instead just a local path?

I didn't get answer, how to install Google Play app from command line.
Given enough privileges (ADB, root, system application) you can use simple terminal commands to install apps:

On a PC:

Run the simple command

adb install &lt;path to .apk file&gt;


and the app will be installed.
This requires adb to be installed and debugging mode enabled.
The file has to be located on the PC.

In adb shell or a terminal on the device:

pm install &lt;path to .apk file&gt;


This is basically the same as the PC method but requires the file to be placed on the phone.
Additionally privileges to install apps are required (ADB shell inherits them from the system, other terminal apps require root)