Termux file system layout

Android OS normally does not provide a write access to system directories such as root file system ("/") for the reasons of security and integrity of system files. This makes difficulties to follow the Filesystem Hierarchy Standard and Termux has to use own.

Packages installation root

All packages must install their data into this directory (installation prefix):

/data/data/com.termux/files/usr

For safety of user data, it is not allowed to create packages installing files outside of this directory.

We often refer to this path as $PREFIX or $TERMUX_PREFIX, latter is used within the context of packaging.

Termux file system hierarchy table

Path	Purpose
/data/data/com.termux/files/usr/bin	Executables used by shell. Combines /bin, /sbin, /usr/bin, /usr/sbin.
/data/data/com.termux/files/usr/etc	Configuration files.
/data/data/com.termux/files/usr/include	C/C++ headers.
/data/data/com.termux/files/usr/lib	Shared objects (libraries), runtime executable data or development-related.
/data/data/com.termux/files/usr/libexec	Executables which should not be run by user directly.
/data/data/com.termux/files/usr/opt	Installation root for sideloaded packages.
/data/data/com.termux/files/usr/share	Non-executable runtime data and documentation.
/data/data/com.termux/files/usr/tmp	Temporary files. Erased on each application restart. Combines /tmp and /var/tmp. Can be freely modified by user.
/data/data/com.termux/files/usr/var	Variable data, such as caches and databases. Can be modified by user, but with additional care.
/data/data/com.termux/files/usr/var/run	Lock files, PID files, sockets and other temporary files created by daemons. Replaces /run.

Important: do not be confused by prefix directory .../usr. It has nothing to do with the real /usr directory which you can find in Linux distributions. Termux never uses a secondary file system hierarchy (/usr) for the packaging purposes.

All hardcoded references to FHS directories should be patched.

Home directory

Termux home directory lives outside of the package installation prefix and is located at this path:

/data/data/com.termux/files/home

This is a place where all user data should be stored. As all application internal data is typically stored on EXT4 or F2FS file system, it supports file access modes, executable permission and special files like symbolic links.

Packages should never install files to the home directory. Exception is only for .deb file scripts, they can be used to prepare initial configuration in $HOME for packages which can't do it on their own.

Android directories

Android OS provides a number of directories, some of them are FHS-compliant. All system directories are read-only and packages should never attempt to install or delete something in them.

Path	Description
/	The root file system. Usually it is a ramdisk, but on modern Android OS versions it is a mounted system partition. Can be restricted by SELinux and not be viewable by ls.
/bin	Symbolic link to /system/bin. Do not add this to PATH to prevent clash of Termux tools with ones provided by Android.
/dev	Standard mount point for file system with device files. Access can be restricted by SELinux, though all important world-writable devices are accessible.
/etc	Symbolic link to /system/etc.
/mnt	Raw mount points of file systems with application and user data.
/proc	Standard directory with runtime process and kernel information. Typically mounted with hidepid=2 option for privacy.
/proc/net	Networking interface statistics. Access restricted since Android 10 for privacy reasons.
/sbin	Directory where special-purpose executables (ADB daemon, dm-verity helper, modem nvram loader, etc). Access is restricted by SELinux and file modes. Do not add this directory to PATH.
/storage	Mounted user's storage volumes. Like /mnt but drive file systems are provisioned by sdcardfs daemon.
/system	The Android OS installation root.
/system/bin	A basic set of command line tools for system purposes and fully-functional ADB shell. Avoid adding this to PATH. Exceptions are allowed only for alternate executable paths, e.g. in case if package is not installed.
/system/xbin	Optional set of system command line tools. Content may vary between ROMs. Do not add this to PATH.