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. unshakable 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 dirfferent usage characteristics on different filesystem.
"Shareable" files are those that can be stored on one host and used on others. "Unshakable" files are those that are not shareable. For example, the files in user home directories are shareable whereas device lock file 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.
We recommend that you read a typeset version of this document rather than the plain text version. In the typeset version, the names of files and directories are displayed in a constant-width font.
Components of filenames that vary are represented by a description of the contents enclosed in "<" and ">" characters,
. Electronic mail address are also enclosed in "<" and ">" but are shown in the usual typeface.
Optional components of filenames are enclosed in "[" and "]" characters adn may be combined with the "<" and ">" convention. For example , if a filename is allowd to occur either with or without an extension, it might be represented by
Variable substrings of directory names and filenames are indicated by "*".
The sections of the text marked as Rationale are explanatory and are non-normative.
*1:a way in which something is usually done, especially within a particular area or activity: the woman who overturned so man conventions of children's literature.
*2:an agreement between countries convering paricular matters, especially one less formal than a treaty.
*3:a large meeting or conference, especially of members of a political party or a particular profession: a convention of retail merchants
Software to predict*1 the location of installed files and directories, and
Users to predict the location of installed files and directories.
Specifying guiding principles for each area of the filesystem,
Specifying the minimum files and directories required,
Enumerating exceptions to the principles, and
Enumerating specific cases where there has been historical conflict.
Independent software suppliers to create applications which are FHS compliant, and work with distributions which are FHS complaint,
OS creators to provide systems which are FHS compliant, and
Users to understand and maintain the FHS compliance of a system.
Local placement of local files is a local issue, so FHS doesn't attempt to usurp*2 system administrators.
FHS addresses issues where file placements need to be coordinated betweeneen multiple parties such as local sites, distributions, applications, documentation, etc.