Where are the system files on Android: structure and access

The internal file structure of the operating system Android is a complex hierarchy inherited from the kernel Linux. Understanding where critical components are physically located is necessary not only for deep customization, but also for diagnosing failures or restoring the device after unsuccessful experiments. The average user rarely encounters these directories directly, since they are hidden from standard file managers for security reasons.

Access to the root partition of the file system is usually limited by superuser rights. This is done in order to prevent accidental deletion of libraries or configuration files that enable the smartphone to boot. However, knowing the exact paths allows engineers and advanced enthusiasts to fine-tune, remove pre-installed software (bloatware) or transfer data to specific memory sections.

In this article we will analyze in detail the logical structure of the partitions, explain the purpose of each directory and provide instructions on how to safely interact with them. You will learn how partitions differ between /system and /data, and also why attempts to write to some of them without unlocking the bootloader are doomed to failure.

The logical structure of file system partitions

The file system Android is not a single monolith, like a disk C: in Windows. It is divided into several independent logical volumes, each of which is mounted at a specific point at boot. This division ensures stability: if the user overfills the data partition, the system files will remain intact and the phone will be able to boot into recovery mode.

The main storage of the operating system is the partition system. This is where the files necessary for the functioning of the Androiditself are located, including frameworks, standard applications and libraries. This partition is mounted in Read-Only mode by default, which protects it from modification by malware or careless actions of the owner.

In addition to the system partition, there is a partition datathat occupies most of the device’s internal memory. All user data is stored here: photos, downloaded documents, application cache and their settings. The separation of these data streams is a fundamental principle of the architecture of Linux-based mobile operating systems.

⚠️ Attention: Direct editing of files in a partition /system without rights Root and an unlocked bootloader is impossible. Attempts to bypass these restrictions through vulnerabilities may lead to loss of warranty or complete bricking of the device.

Modern versions Android (starting from the 10th and especially in 11-13 versions) have introduced a mechanism Project Treblethat more strongly separated the system code and the implementation from the manufacturer. This led to the emergence of new partitions, such as vendor and productthat store drivers and model-specific Samsung, Xiaomi or Pixel software.

System partition: the core of the operating system

The directory /system is the heart of the operating system. When mounted, it becomes readable, and this is where all the basic services are loaded. If you delete a critical file from here, the device will most likely go into a bootloop. Inside this section there are several key subdirectories, knowledge of which is mandatory for any modder.

The folder /system/app contains system applications that were installed at the factory and cannot be removed in the usual way without special rights. At the same time, custom applications that you download from the store are usually located in a different location. The distinction between system and user software here is made at the level of access rights and download priority.

Particular attention should be paid to the folder /system/lib i /system/lib64. The native libraries necessary for the operation of the processor and interaction with the hardware are stored here. The architecture of these libraries depends on the processor of your device: ARM, ARM64 or x86. Inconsistency between library versions can lead to the crash of applications or the entire system.

• 📂 /system/framework —Here are the Java libraries and resources necessary for the operation of the Android interface itself and basic functions.
• 📂 /system/fonts —a directory containing font files that are used throughout the system to display text.
• 📂 /system/media —a storage of system sounds, ringtones, loading animations and wallpapers default.
• 📂 /system/etc —configuration files, including network settings, hosts file and hardware parameters.

It is important to understand that in modern firmware the contents of the partition system can be packed into a single image (system image), which makes it impossible to change individual files without rebuilding the entire image. This complicates the customization process, but increases the integrity of the system.

Data section: storage of user information

Section /data is the most dynamic space in the file system of a smartphone. It is mounted with read-write permissions, allowing applications to save progress, cache, and settings. This is where the folder /data/data (or /data/user/0 in new versions) is located, where the private data of each installed application is located.

Access to the contents of folders inside /data/data is strictly regulated by the sandbox principle. An application cannot read another application's data without explicit system permission or root permission. This is a fundamental mechanism security Androidthat prevents the leakage of passwords and personal information.

In addition to application data, the section /data contains critical system database files, such as settings.db or accounts.db. Damage to these files can lead to resetting all phone settings to factory settings or loss of accounts Google. It also stores a temporary system cache in the folder /data/cache, which can be safely cleared to free up space.

⚠️ Attention: Never delete files with the extension .apk or .odex from the folder /data/app manually through a file manager with root access. This may compromise the integrity of application installations and cause startup errors.

For users who want to transfer applications to a memory card (if such a function is supported by the firmware), it is important to be aware of the existence of symbolic links in this section. The system can emulate internal memory using part of an SD card, creating complex connections between partitions /data and external media.

Hidden sections Vendor, Product and ODM

With the implementation of architecture Project Treble file structure on Android has become more complicated. Sections have appeared that separate the code of the operating system itself from the implementations of equipment manufacturers. The section /vendor contains proprietary drivers and libraries specific to a particular processor (Qualcomm Snapdragon, MediaTek) and device model.

The section /product is designed to store applications and resources that the manufacturer wants to update regardless of the main version. Android. This allows companies like Samsung or Xiaomi to release updates to their interface One UI or MIUI more often than major updates to the OS itself are released from Google.

There is also a section /odm (Original Design Manufacturer), which is used by device manufacturers to store specific settings and drivers if they do not want or cannot place them in the vendorsection. This creates an additional level of abstraction, making the system more modular, but also more difficult for beginners to analyze.

Section	Purpose	Write access	Impact on the system
/system	Basic OS, frameworks	Read only (usually)	Critical (will not load)
/vendor	Hardware drivers, HAL	Read only	Critical (no connection with hardware)
/data	Applications, user settings	Reading and writing	High (data loss)
/cache	Temporary files, OTA updates	Read and write	Low (can be cleared)

Partition manipulation vendor requires special care. If you replace a camera or modem driver with an incompatible one, the corresponding phone modules will simply stop working, even if the system itself boots correctly. Recovery often requires flashing the full stock firmware image.

Why are the partitions divided?

The division into system, vendor and product allows Google to update the underlying Android platform without affecting manufacturers' code. This speeds up the receipt of security updates and new OS versions for users, since manufacturers do not need to re-certify the entire firmware.

Methods of accessing system files

For a regular user who does not have superuser rights, access to system files is only possible through a computer using USB debugging (ADB). This method allows you to view files and even copy some of them (for example, logs or databases), but does not allow you to modify or delete protected system objects.

To gain full access necessary for modification, you need to unlock the bootloader and obtain root access (for example, through Magisk). Only then will file managers with Root support, such as Root Explorer or Solid Explorer, be able to mount partitions in read-write (R/W) mode. Without this step, any write attempts will be rejected by the system kernel.

ADB Command Line provides a powerful tool for navigation. You can connect to the device shell and explore the file structure using standard Linux commands. This is the safest way to study the system, since it does not require installing third-party applications with questionable permissions directly on the phone.

adb shell
ls -la /system
cd /data/data
pm list packages

Using graphical interfaces via ADB is also possible using apps like Android Studio Device File Explorer. This tool visually displays a tree of files and allows you to download them to your computer for analysis, which is convenient for application developers who debug their software.

Precautions and risks of modification

Any interference with the structure of system files is subject to contains potential risks. The most common problem is a violation of access rights (permissions). In Linux-like systems, each file has an owner and a set of rights (read, write, execute). If you change a file manually and forget to restore rights, the system may refuse to read it, resulting in errors.

Another risk is version incompatibility. Firmware files for Android 11 may not work correctly on Android 13 due to changes in the API or library structure. Copying system files between different devices, even of the same brand, often leads to unstable operation, since drivers and configurations are unique to each model.

⚠️ Attention: Interfaces and file paths may vary slightly depending on the version of Android and the manufacturer's shell (One UI, MIUI, ColorOS). Always check the current structure for your specific model before making changes.

If you accidentally deleted an important system file, do not panic. Often the device can be saved by booting into Recovery mode and performing a data reset (Wipe Data), or by flashing the original image via Fastboot or Odin mode (for Samsung). Having saved stock firmware on your computer is a prerequisite for safe experimentation.

Frequently asked questions (FAQ)

Is it possible to delete system files without root access?

It is impossible to completely delete or change system files without root access due to file system limitations. However, using ADB, you can disable some system applications for the current user with the command pm uninstall-user, which will hide them, but will not physically remove them from the section /system.

Where are the files of deleted applications?

After deleting an application, its apk file is erased from /data/app. However, residual data, cache and databases may remain in the folder /data/data/[package_name] until you clear them manually or reset your phone.

Is it safe to change fonts in the folder /system/fonts?

This is a risky operation. If the new font does not contain all the required glyphs or is not in the correct format, the SystemUI may stop launching and you will see a black screen. Always have at hand a way to enter Recovery to restore the original file.

What is the build.prop file and where is it located?

The file build.prop is located in the root of the partition /system. It contains key system build parameters such as device model, Android version, screen density (DPI) and other properties. Editing it allows you to change these parameters, but requires a reboot and caution.

Why is the /sdcard folder not a system one?

The folder /sdcard (or /storage/emulated/0) is an emulation of internal memory for the user, which is actually part section /data. It does not contain OS system files, but is intended solely for storing media files, documents and application data available to the user.