android - adb shell su works but adb root does not

Question

I rooted my unlocked Galaxy S3 (SGH-T999)

Now, I'm trying to run adb root from Windows Command Prompt, however, I'm getting adbd cannot run as root in production builds error. So, the very first thing I checked was whether my phone was really rooted?

So I tried the following:

Open Command prompt

$adb devices // lists my device
$adb shell //goes to shell
$su // opens a 'SuperSu' prompt on my phone and I 'Grant' permission
# // Before following the rooting instructions, I was getting 'no su command found' in the previous step. So, I believe my phone is ROOTED. **Correct me if I'm wrong.**

However, when I do adb root, I get adbd cannot run as root in production builds error. So, I thought, I might have to do some additional stuff beyond what I did above. I tried all the solutions in the following SO questions:

• Launch a script as root through ADB
• adb remount permission denied, but able to access super user in shell -- android
• Unable to run 'adb root' on a rooted Android phone

None of the above worked for me. All they do is give the ROOT access INSIDE of SHELL. I want adb root to work so that I can execute various adb commands WITHOUT going into shell.

Answer 1

By design adb root command works in development builds only (i.e. eng and userdebug which have ro.debuggable=1 by default). So to enable the adb root command on your otherwise rooted device just add the ro.debuggable=1 line to one of the following files:

/system/build.prop
/system/default.prop
/data/local.prop

If you want adb shell to start as root by default - then add ro.secure=0 as well.

Alternatively you could use modified adbd binary (which does not check for ro.debuggable)

From https://android.googlesource.com/platform/system/core/+/master/adb/daemon/main.cpp

#if defined(ALLOW_ADBD_ROOT)
// The properties that affect `adb root` and `adb unroot` are ro.secure and
// ro.debuggable. In this context the names don't make the expected behavior
// particularly obvious.
//
// ro.debuggable:
//   Allowed to become root, but not necessarily the default. Set to 1 on
//   eng and userdebug builds.
//
// ro.secure:
//   Drop privileges by default. Set to 1 on userdebug and user builds.