Error:device not found error prompt after adb shell command

Before entering the ADB shell into the Linux shell environment in CMD, you need to open the Android emulator (this article is for the emulator, not the real machine). If the emulator is started and the Error:device not found error message appears after entering the adb shell command, you can kill the ADB process and then restart the process, and enter the following command in CMD:
ADB kill-server
ADB start-server

Note: It is important to note that in order for the ADB shell command to execute successfully, you must open the Android emulator at the same time.

This is a successful execution, with root access to the Linux system, which executes the Linux command.

Error:device not found error prompt after adb shell command