Question

I am presently working on an WiFi application for Android. I am having trouble trying to access the database on the device. Debugging in the emulator doesn’t work for me, because there is no WiFi support in the emulator. I tried pulling the database file out of the device by using

adb pull data/data/package-name/databases/database-name

But I get the error “Permission denied.”.
In this answer Android: Where are database files stored?, Commonsware has suggested to pull database file by running in debug mode. But it doesn’t work too. Any help on how to debug the database without rooting the device would be much appreciated.

Answer 1

I’ll repeat myself from another answer:

Starting from API level 8 (Android 2.2), if you build the application as debuggable, you can use the shell run-as command to run a command or executable as a specific user/application or just switch to the UID of your application so you can access its data directory.

Copy files to external storage on the device

So if you wish to pull your application database from the device you can launch a debug build of the application from Android Studio, connect with adb shell and run the following command:

run-as com.your.package sh -c "cat ~/databases/db-file.db" > /sdcard/db-file.db

or you can use a shorter version which uses relative paths and by skipping the reference to the home directory ~ can omit the sh -c part too:

run-as com.your.package cat databases/db-file.db > /sdcard/db-file.db

This will copy your db-file.db to the root of your SD card / external storage. Now you can easily get it from there by using file manager, adb pull or whatever else you like. Note that with this approach, there is NO need for your app to have WRITE_EXTERNAL_STORAGE permission, as the copying is done by the shell user who can always write to the external storage.

Copy files directly to the computer

You can also copy a database directly to your computer with the following command:

adb shell 'run-as com.your.package cat databases/db-file.db' > db-file.db

The adb shell command above will not work correctly on Windows host because of the CR/LF symbols conversion, unless you run it from a bash shell or use the undocumented adb exec-out command instead (some comments mention they still cannot get it to work correctly on a Windows machine, so your mileage may vary):

adb exec-out 'run-as com.your.package cat databases/db-file.db' > db-file.db

Write files back to the device

If you modified the file on your computer and wish to write the modifications back to the device use the following command:

adb exec-in 'run-as com.your.package tee databases/db-file.db' < db-file.db

or if you prefer an adb shell version over undocumented exec-in, use the following (but read the concern about the Windows CR/LF conversion above):

adb shell 'run-as com.your.package tee databases/db-file.db' < db-file.db >/dev/null

Status update

All the commands above are still working as of July, 2023