Why and how to read files from Android system using ADB pull command

Issue: Failed to read files from Android system using ADB pull command. Display: Permission denied

Cause: This is caused by file permissions. Use the ls-l command to view file permissions on the Android system:-RW-RW----app_51 app_51 that is, the file only has read and write access to the app_51 user and the App_51 group, and the ADB shell user is the shell, not the AP p_51 user, not in the app_51 group, so there is no permission to read this file.   So there was the Permission denied.     Workaround: Modify the file permissions. Use the SU command to log in with the Superuser.    Modify the file permissions so that other users can read the file. chmod 664 file name if you want to use ADB push to overwrite the file with a file on your computer, you need to give the write permission to the other user, namely: chmod 666 file name