How to set ADB Path in System Variable ? : Android , Mobile automation testing

Check the installation path and if it's installed in C:\Program Files (x86)\Android . This is the default installation location.
So update the PATH variable with following line.
C:\Program Files (x86)\Android\android-sdk\tools\;C:\Program Files (x86)\Android\android-sdk\platform-tools\

Now you can start ADB server from CMD regardless of where the prompt is at.

Android SDK ADB server in CMD screen

How to edit a system variable

Here's a short how-to for the newbies. What you need is the Environment Variables dialog.
  1. Click Start (Orb) menu button.
  2. Right click on Computer icon.
  3. Click on Properties. This will bring up System window in Control Panel.
  4. Click on Advanced System Settings on the left. This will bring up the System Properties window with Advanced tab selected.
  5. Click on Environment Variables button on the bottom of the dialog. This brings up the Environment Variables dialog.
  6. In the System Variables section, scroll down till you see Path.
  7. Click on Path to select it, then the Edit button. This will bring up the Edit System Variable dialog.
  8. While the Variable value field is selected, press the End key on your keyboard to go to the right end of the line, or use the arrow keys to move the marker to the end.
  9. Type in ;C:\Program Files (x86)\Android\android-sdk\tools\;C:\Program Files (x86)\Android\android-sdk\platform-tools\ and click OK.
  10. Click OK again, then OK once more to save and exit out of the dialogs.
That's it! You can now start any Android SDK tool, e.g. ADB or Fastboot, regardless of what your current directory is in CMD. For good measure here's what the dialog looks like. This is where you edit the Path variable.

environment variables