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I want to use my SD card in such a way that I can take the card out and insert into a Windows PC and access files, but have my Camera and other apps freely write to SD card (so data isn't on phone!).

So far if I format as portable, nothing can write to SD card, but if I format as internal, I cant read outside of phone. I'm running AOSP based Android 10 w/ root. Any suggestions? I'd like to just allow full R/W access to all apps to SD card but not encrypt it basically.

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  • Full write access to all apps is not possible. You have to grant permission to each app individually (app requests permission and you have to then select root of sd-card to grant permission to this folder and subfolders). Also write access is only possible via Android/Java API, not via direct file access.
    – Robert
    Commented Aug 14, 2021 at 18:23
  • @Robert feel free to write up an answer. I had a feeling, just some Apps aren't able to use it correctly, like the default LOS Camera App, but Open Camera does, just sucks I need to fight w/ each app. Its not internal storage for a reason! Let me grant global r/w! Damn google, U know what phone I have that does everything (even Miracast!)... My Galaxy S5... Commented Aug 14, 2021 at 19:09

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Since Android 5 write access to the sd-card in portable mode needs to be granted individually for each app. Only apps on a rooted device that are able to use root permissions can bypass this restriction.

For granting write permission the app has to request them in code. Typically it is enough to trigger one write request, e.g. by letting the create a file or folder.

Then Android opens the file application and want's you to select a directory. This is the directory you are granting write permissions for the app, therefore you should select here the path where the sd-card is mounted to, e.g. /storage/A231-7ADF. Usually the sd-card is also shown as quick link on the left side of the files app, so you don't have to know the exact path.

After selecting the sd-card path press the button that is usually something like "Select ..." or "OK". Then you will return to the app you have granted write permission to. To my experience the write request that has triggered the whole process will fail, but every request afterwards will work, if the write-grant-process was performed correctly.

For users doing this the first time it is usually very confusing and you might not be successful on first try. I think it took me several days and multiple attempts before I finally had understood the process and selected the correct folder.

Note that the write permission only works if the app uses the Java/Kotlin Android API to open the files. On file-system level access will be still read-only. This affects especially apps that include generic GNU/Linux native applications that are executed internally as they do not use Android API.

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  • I found this post trying to find a way of using rsync without having to disassemble my phone. Apparently, it is absolutely not possible due to this "security feature". Alternatives are mentioned here: android.stackexchange.com/questions/23224/…
    – Hermann
    Commented Apr 28, 2022 at 21:34
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I'm confused by this question.... exFAT format installed/mounted as SD doesn't require encryption, it does allows windows file transfer with or without the phone. Write/read access is granted by OS app specific. If you set the app to have access, then it will.

Developer options on Android 10 include a "Force allow apps on external Drive" option you could look into even if you don't root. It will make ALL apps eligible to be written directly to external storage, regardless of manifest values. Seems like that is your goal.

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