Stream adb backup output all the way to tar in one line

adb-backup-extract-one-line.sh

#!/bin/bash

# Requires linux or macos
#
# On macos, I used a random open source zlib-uncompress tool that reads stdin and writes stdout only:
#   brew install go
#   go install github.com/odeke-em/zlib-cli/cmd/zlib-uncompress@latest
# And add $HOME/go/bin to my PATH (or add to the command)
#
# This will take adb backup output and stream it all the way to tar with verbose output
# This lets us see contents of the backup as they come off the phone and gives some indication of progress
#
# I found a copy of some old adb docs, here http://adbcommand.com/adbshell , the latest version of adb has
# deprecated adb backup and does not appear to include docs in the help output anymore (2022-06-04)
# I've copied them here as well:
#
# adb backup [-f file] [-apk | -noapk] [-obb | -noobb] [-shared | -noshared] [-all] [-system | [-nosystem] package_names
#
# Write an archive of the device's data to file. If you do not specify a file name, the default file is backup.adb. 
# The package list is optional when you specify the -all and -shared options. The following describes the usages for
# the other options:
#    -apk | -noapk: Back up or do not back up .apk files. The default value is -noapk.
#    -obb | -noobb: Back up or do not back up .obb files. The default value is -noobb.
#    -shared | -noshared: Back up or do not back up shared storage. The default value is -noshared.
#    -all: Back up all installed apps.
#    -system | -nosystem: Include or do not include system apps when backing up all installed apps (-all). The default value is -system.
#
# * Replace the string in the command below with your chosen options

# Typically you will want to create a new backup directory each time you use this
mkdir my-backup-dir

./adb backup -f /dev/stdout 'options go here' | tail -c +157 | zlib-uncompress | tar -C my-backup-dir -xvf -

# Example with my real options:
./adb backup -f /dev/stdout -all -apk -nosystem | tail -c +157 | zlib-uncompress | tar -C backup-2 -xvf -

# Notes:
# * Part of the offset passed to tail (+25 of it) is sourced here:
#   https://stackpointer.io/mobile/android-adb-backup-extract-restore-repack/372/
#   The remaining 132 is the prompt telling the user to unlock their phone, you may
#   potentially need to adjust this based on your adb version
# * The app manifest has an option to disable backups, which probably includes adb
#   backup (but since it's deprecated it seems like docs don't specify this anymore)
#   For me, this seems to mean very few apps get backed up with this :(
#   https://developer.android.com/about/versions/12/behavior-changes-12#backup-restore