How to Create a Flashable Zip for Android System Mods

By Kamil AnwarUpdated on June 27, 2023

Kamil is a certified Systems Analyst

If you’re an Android developer who wants to create apps intended for /system partition (such as root apps), there are certain instances where you’ll want to create a flashable .zip for your app. This is so that the app files can properly be installed to the /system partition.

A few other uses of flashable .zips include:

Modifying the DPI
Applying a custom font
Applying a custom boot animation
Removing or adding system apps

Instructing your users to mess around in the file system and manually move files is a time waster for everyone involved – creating a flashable .zip is a much more convenient route. This Appual’s guide will show you how to create a flashable zip for Android.

We will also show you an addon.d script, so that custom system changes will survive a dirty ROM flash – thus, users will not need to re-flash your zip for each update.

Requirements:

A root file explorer (MiXplorer, Solid Explorer)
ZipSigner (for signing zips) or the MiX Signer plug-in if you use MixPlorer
A Nandroid backup is highly recommended

You should also prepare all the files that are going into the zip – APKs, configs, boot animations, etc. Have everything organized before we begin, because this is a delicate process.

Template of a Custom Zip

If you want to download a template zip that you can customize to your own needs, or use it as a base for creating a flashable zip, you can grab them here:

TEMPLATE SCRIPT: DOWNLOAD LINK (basic commands / you have to add your custom values: apps, paths of ringtones, bootanimation…)
TEMPLATE ZIP: DOWNLOAD LINK (examples are always welcome to better understand an explanation. It can help to understand how to structure your files).

The template should be enough to start using a custom script.

You’ll need to remember these main paths, because these are the things in the /system partition that your flashable zips will typically target:

addon.d => backup script to survive a dirty flash (used by GApps package for instance)
app and priv-app => system apps to add or remove
etc => host file
fonts => your font
media => your bootanimation.zip
media > audio > alarms => sounds for alarms
media > audio > notifications => sounds for notifications
media > audio > ringtones => sounds for ringtones
media > audio > ui => sounds for various things such as low battery, unlock, camera,..
root of /system for build.prop file

Always remember that files removed from these paths will be re-installed after a dirty flash, and files that have been manually added will be removed. This is why its necessary to create a script that makes a backup of your /system mods.

Example of an Update-Script

ui_print("+-------------------------------------+");
ui_print("| CLEAN FLASH SCRIPT |");
ui_print("| |");
ui_print("| by Primokorn |");
ui_print("+-------------------------------------+");
run_program("/sbin/busybox", "umount", "/system");
run_program("/sbin/busybox", "mount", "/system");
ui_print(" ");
ui_print("***Deleting bloatwares***");
delete_recursive(
"/system/app/adaway.apk",
"/system/app/AdAway",
"/system/app/BasicDreams",
"/system/app/BookmarkProvider",
"/system/app/Calendar",
"/system/app/CalendarWidget",
"/system/app/CMFileManager",
"/system/app/CMWallpapers",
"/system/app/DeskClock",
"/system/app/Eleven",
"/system/app/Email",
"/system/app/ExactCalculator",
"/system/app/Exchange2",
"/system/app/Gello",
"/system/app/HexoLibre",
"/system/app/Jelly",
"/system/app/LiveWallpapersPicker",
"/system/app/LockClock",
"/system/app/messaging",
"/system/app/MiXplorer",
"/system/app/NexusLauncher",
"/system/app/Phonograph",
"/system/app/PhotoTable",
"/system/app/PicoTts",
"/system/app/PicoTTS",
"/system/app/ResurrectionStats",
"/system/app/SoundRecorder",
"/system/app/Terminal",
"/system/app/TugaBrowser",
"/system/app/Wallpaper",
"/system/app/WallpaperPickerGoogle",
"/system/priv-app/AudioFX",
"/system/priv-app/Chrome",
"/system/priv-app/Gallery2",
"/system/priv-app/MusicFX",
"/system/priv-app/OnePlusCamera",
"/system/priv-app/OnePlusGallery",
"/system/priv-app/OnePlusMusic",
"/system/priv-app/Recorder",
"/system/priv-app/Screencast",
"/system/priv-app/Snap",
"/system/priv-app/SnapdragonCamera",
"/system/priv-app/SnapdragonGallery",
"/system/priv-app/WeatherManagerService",
"/system/priv-app/WeatherProvider",
"/system/priv-app/Tag"
);
ui_print("Installing apps and mods, etc");
show_progress(8.800000, 5);
package_extract_dir("system", "/system/");
ui_print("***Fixing permissions***");
set_perm(0, 0, 0755, "/system/addon.d/99-dirty.sh");
set_perm(0, 0, 0644, "/system/etc/gps.conf");
set_perm(0, 0, 0644, "/system/fonts/Roboto-Regular.ttf");
set_perm(0, 0, 0644, "/system/media/audio/ringtones/PlasticRing.ogg");
set_perm(0, 0, 0644, "/system/priv-app/Phonesky.apk");
set_perm(0, 0, 0644, "/system/priv-app/microG.apk");
set_perm(0, 0, 0644, "/system/priv-app/Gsam.apk");
set_perm(0, 0, 0644, "/system/priv-app/BBS.apk");
set_perm(0, 0, 0644, "/system/priv-app/V4A-Magisk.apk");
run_program("/sbin/busybox", "mount", "/data");
package_extract_dir("data", "/data/");
set_perm(0, 0, 0755, "/data/local/afscript.sh");
show_progress(8.800000, 5);
run_program("/sbin/busybox", "umount", "/data");
run_program("/sbin/busybox", "umount", "/system");
ui_print(" ");
ui_print("Done.");
ui_print("Ready to reboot.");

Note: ui_print(” “); is for text message. These lines don’t do anything.

You should always unmount and re-mount the partition before working on it.

run_program("/sbin/busybox", "umount", "/system");
run_program("/sbin/busybox", "mount", "/system");

To remove system components / apps, put a comma at the end of each line, except the last one.

delete_recursive(
"/system/app/adaway.apk",
"/system/app/AdAway",
........................
"/system/priv-app/WeatherProvider",
"/system/priv-app/Tag"
);

Extract the system files you want to install.

package_extract_dir("system", "/system/");

Set the file permissions.

set_perm(0, 0, 0755, "/system/addon.d/99-dirty.sh");
..............
set_perm(0, 0, 0644, "/system/priv-app/V4A-Magisk.apk");

Do the same thing but for the /data folder. So you will mount the partition, extract the data you want to add, and set the permissions.

run_program("/sbin/busybox", "mount", "/data");
package_extract_dir("data", "/data/");
set_perm(0, 0, 0755, "/data/local/afscript.sh");

Next you will unmount the modified partitions.

run_program("/sbin/busybox", "umount", "/data");
run_program("/sbin/busybox", "umount", "/system");

Example of Addon.D script

#!/sbin/sh
# 
# /system/addon.d/99-dirty.sh
# /system is formatted and reinstalled, then thes files are restored.
#

. /tmp/backuptool.functions

list_files() {
cat <<EOF
addon.d/99-dirty.sh
fonts/Roboto-Regular.ttf
media/audio/ringtones/PlasticRing.ogg
priv-app/BBS.apk
priv-app/Gsam.apk
priv-app/microG.apk
priv-app/PhoneSky.apk
priv-app/V4A-Magisk.apk
etc/gps.conf
etc/hosts
EOF
}

case "$1" in
backup)
list_files | while read FILE DUMMY; do
backup_file $S/"$FILE"
done
;;
restore)
list_files | while read FILE REPLACEMENT; do
R=""
[ -n "$REPLACEMENT" ] && R="$S/$REPLACEMENT"
[ -f "$C/$S/$FILE" ] && restore_file $S/"$FILE" "$R"
done
rm -rf /system/app/adaway.apk
rm -rf /system/app/AdAway
rm -rf /system/app/BasicDreams
rm -rf /system/app/BookmarkProvider
rm -rf /system/app/Calendar
rm -rf /system/app/CalendarWidget
rm -rf /system/app/CMFileManager
rm -rf /system/app/CMWallpapers
rm -rf /system/app/DeskClock
rm -rf /system/app/Eleven
rm -rf /system/app/Email
rm -rf /system/app/ExactCalculator
rm -rf /system/app/Exchange2
rm -rf /system/app/Gello
rm -rf /system/app/HexoLibre
rm -rf /system/app/Jelly
rm -rf /system/app/LatinIME
rm -rf /system/app/LiveWallpapersPicker
rm -rf /system/app/LockClock
rm -rf /system/app/messaging
rm -rf /system/app/MiXplorer
rm -rf /system/app/NexusLauncher
rm -rf /system/app/Nova.apk
rm -rf /system/app/Phonograph
rm -rf /system/app/PhotoTable
rm -rf /system/app/PicoTts
rm -rf /system/app/PicoTTS
rm -rf /system/app/ResurrectionStats
rm -rf /system/app/SoundRecorder
rm -rf /system/app/Terminal
rm -rf /system/app/TugaBrowser
rm -rf /system/app/Wallpaper
rm -rf /system/app/WallpaperPickerGoogle
rm -rf /system/priv-app/AudioFX
rm -rf /system/priv-app/Chrome
rm -rf /system/priv-app/Gallery2
rm -rf /system/priv-app/LatinIME
rm -rf /system/priv-app/MusicFX
rm -rf /system/priv-app/OnePlusCamera
rm -rf /system/priv-app/OnePlusGallery
rm -rf /system/priv-app/OnePlusMusic
rm -rf /system/priv-app/Recorder
rm -rf /system/priv-app/Screencast
rm -rf /system/priv-app/SnapdragonCamera
rm -rf /system/priv-app/SnapdragonGallery
rm -rf /system/priv-app/Snap
rm -rf /system/priv-app/Trebuchet
rm -rf /system/priv-app/WeatherManagerService
rm -rf /system/priv-app/WeatherProvider
rm -rf /system/priv-app/Tag
;;
pre-backup)
# Stub
;;
post-backup)
# Stub
;;
pre-restore)
# Stub
;;
post-restore)
# Stub
;;
esac

Create a list of files you want to keep after a dirty flash.

list_files() {
cat <<EOF
addon.d/99-dirty.sh
fonts/Roboto-Regular.ttf
media/audio/ringtones/PlasticRing.ogg
priv-app/BBS.apk
priv-app/Gsam.apk
priv-app/microG.apk
priv-app/PhoneSky.apk
priv-app/V4A-Magisk.apk
etc/gps.conf
etc/hosts
EOF
}

RM -RF the files you don’t want to be installed after a dirty flash (system files you removed in your modification that will be re-installed from a dirty flash)

rm -rf /system/app/adaway.apk
rm -rf /system/app/AdAway
rm -rf /system/app/BasicDreams
rm -rf /system/app/BookmarkProvider
................................................
rm -rf /system/priv-app/WeatherProvider
rm -rf /system/priv-app/Tag
;;

How to Create a Flashable Android Zip

We’ll be using MiXplorer for this, as it’s the best root explorer and file manager for Android, hands down.

First select all your folders that will be included in the zip, and choose Archive.
Confirm the creation of your archive file, give it a name and choose Store.
Your flashable zip will be created, so select the zip file and then Sign it (using MiX signer plugin)
Now select TestKey to just check it for signature errors.
You can now flash the zip – recommend moving it to /SDcard for easily finding it from custom recovery.

Final Notes

Your flashable zip needs to be installed after a clean flash, or after wiping the /system partition and doing a dirty flash of your ROM. The updater-script will remove and add the system files you specified in your script – but leave the addon.d script alone, because it will do its job without any interference from you.

After your first installation, thoroughly check the /system partition to make sure everything is correct – files are removed, etc. Maybe you had a typo in a file name and it wasn’t removed, it happens.

Requirements:

Template of a Custom Zip

Always remember that files removed from these paths will be re-installed after a dirty flash, and files that have been manually added will be removed. This is why its necessary to create a script that makes a backup of your /system mods.

Example of Addon.D script

How to Create a Flashable Android Zip

Final Notes

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