Unix Filesystem Hierarchy Standard
By Filesystem Hierarchy Standard Group
Edited by Rusty Russell, Daniel Quinlan, and Christopher Yeoh
Edited by Rusty Russell, Daniel Quinlan, and Christopher Yeoh
This standard consists of a set of requirements and guidelines for file and directory placement under UNIX-like operating systems. The guidelines are intended to support interoperability of applications, system administration tools, development tools, and scripts as well as greater uniformity of documentation for these systems.
The Filesystem
This standard assumes that the operating system underlying an FHS-compliant file system supports the same basic security features found in most UNIX filesystems.
It is possible to define two independent distinctions among files: shareable vs. unshareable and variable vs. static. In general, files that differ in either of these respects should be located in different directories. This makes it easy to store files with different usage characteristics on different filesystems.
"Shareable" files are those that can be stored on one host and used on others. "Unshareable" files are those that are not shareable. For example, the files in user home directories are shareable whereas device lock files are not.
"Static" files include binaries, libraries, documentation files and other files that do not change without system administrator intervention. "Variable" files are files that are not static.
Historical UNIX-like filesystem hierarchies contained both static and variable files under both /usr and /etc.
