about adb backup

adb backup and adb restore are obscure (not mentioned in adb --help) and depracated features of adb but no root needed

adb backup and adb restore commands documented here

file generated by adb backup is optionally compressed, optinally encrypted tar (pax (kinda) format (don't confuse with pax command)) container

files and pax headers in tar archive need to be be in secific order and have specific names, so extracting and creating archive probably won't work (adb restore silently fails)

you can update files in tar archive without extracting everything using 7zz (7-Zip for Linux: console version) u command

here is help for old version of 7z.exe but most command line options are same as 7zz

abpy.py is python3 script for files generated by adb backup

abpy.py depends on PyCryptodome if using encryption

example: modify /data/data/com.gdpsedi.geometrydashsubzero/CCLocalLevels.dat on android no root using linux computer

1. backup com.gdpsedi.geometrydashsubzero's files into backup.ab:

   $ adb backup com.gdpsedi.geometrydashsubzero
   WARNING: adb backup is deprecated and may be removed in a future release

2. convert backup.ab to backup.tar:

   $ python3 abpy.py ab2tar if=backup.ab of=backup.tar

3. find CCLocalLevels.dat path in list of files in backup.tar:

   $ 7zz l backup.tar | grep -F CCLocalLevels.dat
   2023-04-13 11:11:51 .....          733         1024  apps/com.gdpsedi.geometrydashsubzero/r/CCLocalLevels.dat

4. extract with full path apps/com.gdpsedi.geometrydashsubzero/r/CCLocalLevels.dat from backup.tar:

   $ 7zz x backup.tar apps/com.gdpsedi.geometrydashsubzero/r/CCLocalLevels.dat
   
   7-Zip (z) 22.01 (x64) : Copyright (c) 1999-2022 Igor Pavlov : 2022-07-15
    64-bit locale=en_US.UTF-8 Threads:12, ASM
   
   Scanning the drive for archives:
   1 file, 6880256 bytes (6719 KiB)
   
   Extracting archive: backup.tar
   --
   Path = backup.tar
   Type = tar
   Physical Size = 6880256
   Headers Size = 14336
   Code Page = UTF-8
   Characteristics = POSIX PREFIX PAX path ASCII
   
   Everything is Ok
   
   Size:       733
   Compressed: 6880256

5. edit apps/com.gdpsedi.geometrydashsubzero/r/CCLocalLevels.dat
6. update apps/com.gdpsedi.geometrydashsubzero/r/CCLocalLevels.dat to backup.tar:

   $ 7zz u backup.tar apps/com.gdpsedi.geometrydashsubzero/r/CCLocalLevels.dat
   
   7-Zip (z) 22.01 (x64) : Copyright (c) 1999-2022 Igor Pavlov : 2022-07-15
    64-bit locale=en_US.UTF-8 Threads:12, ASM
   
   Open archive: backup.tar
   --
   Path = backup.tar
   Type = tar
   Physical Size = 6880256
   Headers Size = 14336
   Code Page = UTF-8
   Characteristics = POSIX PREFIX PAX path ASCII
   
   Scanning the drive:
   1 file, 824 bytes (1 KiB)
   
   Updating archive: backup.tar
   
   Keep old data in archive: 6 folders, 17 files, 6861172 bytes (6701 KiB)
   Add new data to archive: 1 file, 824 bytes (1 KiB)
   
       
   Files read from disk: 1
   Archive size: 6880256 bytes (6719 KiB)
   Everything is Ok

7. get info about backup.ab:

   $ python3 abpy.py abinfo if=backup.ab
   ver=5
   compr

8. convert backup.tar to backup.ab with that info:

   $ python3 abpy.py tar2ab if=backup.tar of=backup.ab compr ver=5

9. restore the new backup.ab:

   $ adb restore backup.ab
   WARNING: adb restore is deprecated and may be removed in a future release
   Now unlock your device and confirm the restore operation.

stuff I found related to adb backup

• https://github.com/nelenkov/android-backup-extractor/
• https://nelenkov.blogspot.com/2012/06/unpacking-android-backups.html
• https://forum.xda-developers.com/t/guide-how-to-extract-create-or-edit-android-adb-backups.2011811/
• https://sourceforge.net/projects/android-backup-processor/files/