How to extract or unpack an .ab file (Android Backup file)

Question

I am running an android 4.0.3 device, and I want to extract the back up file created by : ``` adb backup -f ~/data.ab -noapk app.package.name ``` The above line works inside the CMD (windows) and I am able to get the data.ab file inside the '~' directory. What I can't do is extact that file using CMD . I tried the below two methods. ``` dd if=data.ab bs=1 skip=24 | openssl zlib -d | tar -xvf - dd if=data.ab bs=1 skip=24 | python -c "import zlib,sys;sys.stdout.write(zlib.decompress(sys.stdin.read()))" | tar -xvf - ``` I get the below error I tried extracting it via CYGWIN, however, I failed too. Where should I do the extraction ? In which directory should my command prompt be ? Any insights ?

Accepted Answer

As per https://android.stackexchange.com/a/78183/239063 you can run a one line command in Linux to add in an appropriate tar header to extract it.

```
( printf "\x1f\x8b\x08\x00\x00\x00\x00\x00" ; tail -c +25 backup.ab ) |  tar xfvz -
```

Replace backup.ab with the path to your file.

How to extract or unpack an .ab file (Android Backup file)

Solution

Problem