Directory structure

As a directory structure (including the directory tree or folder structure called ) the hierarchical form of a file system from a single computer and in a broader sense a directory service objects (users, devices, services, and file shares ) of a company network is referred to in the strict sense. Usual is a tree structure that starts at a root (English root) and then arbitrarily branched. In the following the directory structure of a file system is described, to the directory service of a corporate network see there.

Properties

In each level of the tree both files and directories can be located, the latter form the next level of the tree. The directory structure thus arises from the fact that directories again ( sub) can contain directories, starting from a root directory. Each directory can contain both subfolders and file entries. Name and position of each entry ( file or directory) can be specified by a corresponding path that starts at the root and all to be run through directories listing. Example: In the adjacent figure there are in the Unix tree, the file / home / user- name / Foto.png, ie starting from the root directory / subdirectory in the home, including user name in the directory the file is located Foto.png.

The possibility of cross-links (folder or file associations, english links, even across planes) to create power, strictly speaking, from the tree form the directory structure of a network, because of the strict hierarchy is lost. According to the same file can be specified in certain circumstances through different paths.

Restrictions to a single plane ( trivial tree ) are known from embedded systems. Older file systems, as they are partly still in use on mainframes, have a relatively rigid directory structure with partially well-defined number of levels, without the ability to easily create subdirectories.

Permissions

The first authorization concepts gave each user a separate directory just above the root level. Appeals from this period can still be found in the special root user account on Unix, which initially has all system privileges. Although now evolved significantly, which is still commonly used Unix authorization concept still holds close connection to the directory structure by per directory (and per file ) to a user ( the owner), for a defined group of users, and for all the rest each an authorization is granted. A real n: m assignment ( that is, the attribution of rights / prohibited for each user separately ) between directories or files and authorized user accounts, making it therefore not yet possible, do not want to create a separate group for each directory you. Newer solutions like ACLs provide more convenient ways.

Background

Many operating systems provide the ability to partition hard disks and disk systems. Such partitions and entire drives can be formatted with a file system, that is, it is created an empty directory structure and put the assigned disk space under the administration of the file system.

Individual file systems on Unix, Linux or Mac OS X at the desired location hooked in the directory structure of the computer (mounted ) and then expand the tree to another, in itself optionally branched tree branch. Its origin is also referred to as the mount point. Other operating systems, such as DOS, Microsoft Windows or OpenVMS, awarded for each filesystem a unique name so that multiple trees co-exist. Since Windows 2000, points can also be used in the NTFS file system mount.

Recent developments for file systems also make the consumer market of operating systems in the future some techniques of relational databases or object-oriented structuring available. Conventional directory structures with hierarchical facility will be only one among many ways to create new databases, modify, retrieve and read.

Standardization

Mainly in the area of ​​Unix-like systems, there are efforts to standardize the directory structure regardless of the operating system. Through a unified directory structure, for example, certain executable files or configuration files can always be found in the same place, what the software development, migration from one operating system to another and the incorporation of users greatly simplified. In addition to POSIX, SUS and LSB standards, which describe all the directory structure, the Filesystem Hierarchy Standard (FHS) is a significant normalization of a directory structure.