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 inverted because of the root of the tree is said to be at the top of the hierarchy, and the branches of directories and subdirectories stretch below the root.

The directory / is the root directory at 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 subdirectory 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.

Subdirectories 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 subdirectory /boot is used for storing files needed to boot the system.

Most important directories on the system by name and purpose.

/usr  -  Installed software, shared libraries, include files, and static read-only program

data. Important subdirectories include:

- /usr/bin: User commands.

- /usr/sbin: System administration commands.

- /usr/local: Locally customized software.

/etc -  Configuration files specific to this system.

/var  - 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 - Runtime 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. (This directory consolidates /var/run and /var/lock from older versions of Red Hat Enterprise Linux.)


/home - Home directories where regular users store their personal data and configuration files.

/root -  Home directory for the administrative superuser, root.

/tmp - A world-writable space for temporary files. Files that have not been accessed, changed, or modified for 10 days are deleted from this directory automatically. Another temporary directory exists, /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 that are used by the system to access hardware.