Filesystem Hierarchy Standard

The Filesystem Hierarchy Standard (FHS) defines the directory structure and directory contents in Linux distributions. It is maintained by the Linux Foundation. The latest version is 3.0, released on 3 June 2015. In the FHS, all files and directories appear under the root directory /, even if they are stored on different physical or virtual devices. Some of these directories only exist on a particular system if certain subsystems, such as the X Window System, are installed. Most of these directories exist in all Unix-like operating systems and are generally used in much the same way; however, the descriptions here are those used specifically for the FHS, and are not considered authoritative for platforms other than Linux. Most Linux distributions follow the Filesystem Hierarchy Standard and declare it their own policy to maintain FHS compliance. GoboLinux and NixOS provide examples of intentionally non-compliant filesystem implementations.