> adb shell sh-4.1$ su Permission denied
I have rooted my phone successfully. I know this because I'm able to install apps on SD card and I have a program called SD Maid that is able to operate with root permissions.
You might need to activate adb root from the developer settings menu. If you run adb root from the cmd line you can get:
root access is disabled by system setting - enable in settings -> development options
root access is disabled by system setting - enable in settings -> development options Once you activate the root option (ADB only or Apps and ADB) adb will restart and you will be able to use root from the cmd line.
There is an app on Google Play called ADBD Insecure by Chainfire. This app lets you run adbd in root mode if your device is rooted when running the devices Stock ROM. I just recently found out about this app.
The version on Google Play is not Free, but there is a free version available. The link to the free version is linked in the description of the application in Google Play.
What is great about this app, it works with Stock ROMs that have been rooted. If you are using a custom kernel, or a custom ROM, you probably won't need this application. But if you are still using a stock rom, just rooted, then you may want to get this application for your device.