title: what 's difference between android system user and linux root user
body: <p>When I connect my phone to computer,then I use "adb shell" command to communicate with my phone and input ps command to output processes info that currently run on my phone,I find two special users,one is root,the other is system,as far as I know,android based on linux,so root user is the bigest authority user,but I confuse with system user,maybe I can consider it as a normal user in linux system,But it is special in Android,it has a lot of permissions related to android,so Can someone tell me the real different between root user and system user,and why android need to add a system user?thanks:)</p>