The Linux File System Hierarchy

The Linux File System Hierarchy

All files on a Linux system are stored on file systems which are organized into a single inverted tree of directories, known as a file system hierarchy. This tree is invited because the root of the tree is said to be at the top of the hierarchy, and the branches of directories and sub-directories stretch below the root.

The directory / is the root directory at of the top of the file system hierarchy. The / character is also used as a directory separator in file names. For example, if etc is a sub-directory of the / directory, we could call that directory /etc . likewise, if the /etc directory contained a file named issue, we could refer to that file as /etc/ issue.

Sub-directories of / are used for standardized purposes to organize files by type and purpose. This makes it easier to find files. For example, in the root directory, the sub-directory /boot is used for storing files needed to boot the system.

The following table lists some of the most important directories on the system by name and purpose.

Important Linux directories

Location	Purpose
/usr	Installed software, shared libraries, include files, and static read –only program data. Important sub-directories include: -/usr/bin: User commands. -/usr/sbin: System administration commands. -usr/local: Locally customized software.
/etc	Variable data specific to this system that should persist between boots. Files that dynamically change (e.g. databases, cache directories, log files, printer spooled documents, and website content) may be found under /var.
/run	Run-time data for processes started since the last boot. This includes process ID files and lock files, among other things. The contents of this directory are recreated on reboot.
/root	Home directory for the administrative super-user, root.
/home	Home directories where regular users store their personal data and configuration files.
/tmp	A world-writable space for temporary files. Files which are more than 10 days old are deleted from this directory automatically. Another temporary directory exist, /var /tmp, in which files that have not been accessed, changed, or modified in more than 30 days are deleted automatically.
/boot	Files needed in order to start the boot process.
/dev	Contains special device files which are used by the system to access hardware.
/dev	Contains special device files which are used by the system to access hardware.

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