########################################################################################
# Run on Linux: go wireless for adb, attach USB drive to phone, and inspect its paths.
# 6C2A-1618 is an on-phone microSD card's ID, 8145-191C is the attached USB drive's ID.
#
# Your adb path will vary; it's not shown in full here because it was added to $PATH,
# but on Linux was /home/me/.buildozer/android/platform/android-sdk/platform-tools/adb.
# You can also run 'adb shell' just once, and omit the 'adb shell ' prefix on commands.
#
# Note: wireless adb connection steps have also changed in Android 11; enable it in dev 
# options, pair if needed (see https://developer.android.com/studio/command-line/adb).
########################################################################################

## Where necessary 

$ adb tcpip 5555              # see docs link above
$ adb connect 192.168.1.2     # also: adb pair 192.168.1.2:xxxxx

## And disconnect from pc, plug in drive

########################################################################################
# The microSD card is still addressable by path in Android 11, but USB drives are not
########################################################################################

## Device root

$ adb shell ls /
...much, including these
mnt
sdcard
storage
$ 

## All "volumes"

$ adb shell ls /storage
6C2A-1618
emulated
self
$ 

## Internal storage (same as /sdcard: see ahead)

$ adb shell ls /storage/emulated/0
Admin
Admin-Mergeall
Alarms
Android
...etc
MY-STUFF
...etc
$
$ adb shell ls /storage/emulated/0/Android
data
media
obb
$

## The microSD card

$ adb shell ls /storage/6C2A-1618
Admin-Mergeall
Alarms
Android
...etc
MY-STUFF
...etc
$ 
$ adb shell ls /storage/6C2A-1618/Android
data
obb
$ 

## ==>  BUT the USB drive is MIA  <==

$ adb shell ls /storage/8145-191C
ls: /storage/8145-191C: No such file or directory
$
$ adb shell ls /storage/8145-191C/Android
ls: /storage/8145-191C/Android: No such file or directory 
$ 

########################################################################################
# Try /mnt/media_rw: one file explorer uses this, but it requires permissions or root
########################################################################################

## The mount root works

$ adb shell ls /mnt
androidwritable
appfuse
asec
expand
installer
knox
media_rw
obb
pass_through
product
runtime
sdcard
sde
secure
shell
user
vendor
$ 

## But its device folder is off-limits (for both microSD and USB)

$ adb shell ls /storage/6C2A-1618/Android
data
obb
$ 
$ adb shell ls /mnt/media_rw
ls: /mnt/media_rw: Permission denied
$ 
$
$ adb shell ls /mnt/media_rw/6C2A-1618/Android
ls: /mnt/media_rw/6C2A-1618/Android: Permission denied
$ 
$
$ adb shell ls /mnt/media_rw/8145-191C
ls: /mnt/media_rw/8145-191C: Permission denied
$ 
$ adb shell ls /mnt/media_rw/8145-191C/Android
ls: /mnt/media_rw/8145-191C/Android: Permission denied
$ 
$ adb shell ls /mnt/media_rw/8145-191C/Android/data
ls: /mnt/media_rw/8145-191C/Android/data: Permission denied
$ 

## Maybe it's time for a rootable phone?

$ adb root
adb cannot run as root in production builds
$ 
$ adb shell sudo ls /mnt/media_rw
/system/bin/sh: sudo: inaccessible or not found
$ 
$ adb shell su -c ls /mnt/media_rw
/system/bin/sh: su: inaccessible or not found
$ 

########################################################################################
# Alternate paths to internal storage (whose root is still accessible to Python code)
########################################################################################

## Internal storage (same as /sdcard on this device)

$ adb shell ls -l /storage/emulated/0
total 86
drwxrwx---  2 root everybody 3488 2020-09-09 17:00 Admin
drwxrwx---  3 root everybody 8192 2021-01-02 17:51 Admin-Mergeall
drwxrwx---  2 root everybody 3488 2020-07-23 02:08 Alarms
drwxrwx---  6 root everybody 3488 2020-12-29 16:10 Android
...etc
drwxrwx--- 13 root everybody 3488 2020-12-30 16:00 MY-STUFF
drwxrwx---  5 root everybody 3488 2020-07-26 14:37 my-OTHER-STUFF
drwxrwx---  3 root everybody 3488 2020-12-30 17:47 qpython
-rw-rw----  1 root everybody    4 2020-12-31 15:23 xxx.txt
$ 

## The many paths to your stuff (on this device)

$ adb shell ls /storage/self
primary
$ 
$ adb shell ls -l /storage/self/primary/Android
total 14
drwxrwx--x 94 root sdcard_rw 8192 2021-01-01 21:08 data
drwxrwx---  2 root everybody 3488 2020-12-29 13:42 media
drwxrwx--x 10 root sdcard_rw 3488 2021-01-05 06:39 obb
$ 
$ adb shell ls -l /storage/emulated/0/Android
total 14
drwxrwx--x 94 root sdcard_rw 8192 2021-01-01 21:08 data
drwxrwx---  2 root everybody 3488 2020-12-29 13:42 media
drwxrwx--x 10 root sdcard_rw 3488 2021-01-05 06:39 obb
$ 
$ adb shell ls -l /sdcard/Android
total 14
drwxrwx--x 94 root sdcard_rw 8192 2021-01-01 21:08 data
drwxrwx---  2 root everybody 3488 2020-12-29 13:42 media
drwxrwx--x 10 root sdcard_rw 3488 2021-01-05 06:39 obb
$

## Transitive links (a historical legacy of obfuscation)

$ adb shell ls -l /sdcard
lrw-r--r-- 1 root root 21 2008-12-31 07:00 /sdcard -> /storage/self/primary
$ 
$ adb shell ls -l /storage/self/primary
lrwxrwxrwx 1 root root 19 2021-01-05 06:39 /storage/self/primary -> /storage/emulated/0
$ 
$ adb shell ls -l /mnt/sdcard
lrwxrwxrwx 1 root root 21 2019-06-03 13:32 /mnt/sdcard -> /storage/self/primary
$

########################################################################################
# Back to wired (where required)
########################################################################################

## Where necessary and desired

$ adb disconnect
disconnected everything
$
$ adb usb
restarting in USB mode