Causes of File Reading failure using adb pull command from android system and Solutions

Problem: An error occurred while reading the file from the android system using the adb pull command. Display: Permission denied

Cause: it is caused by file permissions. Run the ls-l command to view the file permissions in android:-rw ---- app_51 app_51. That is to say, only app_51 users and app_51 groups have the read and write permissions on the file, the adb shell user is shell, neither app_51 user nor app_51 group, so the user has no permission to read the file. So Permission denied appears. Solution: Modify the File Permission. Use the su command to log on to the Super User. Modify the File Permission so that other users can read the file. Chmod 664 file name if you want to use adb push to overwrite this file with files on your computer, you need to grant the write permission to other users, that is, the chmod 666 file name.