UNIX OPERATING SYSTEM

UNIX File System



UNIX File System

UNIX has hierarchal file system. UNIX files and directories are arranged in a systematic way, like a tree structure. The root directory is represented by the slash symbol (/). It serves as the root of this directory tree. By file system layout, we mean the arrangement of files and directories in a directory tree. It does not mean the actual physical format of the disk drive but shows only logical arrangement. Directories in UNIX are named and arranged in a fashion that has particular meaning for users. Every directory contains a particular set of files related to some defined purpose or task. For example, all files in the /etc directory are related to some sort of system configuration task. Similarly, the home directories of all users are usually kept in the /home directory.

UNIX File System

There are two major types of file system hierarchies used in UNIX distributions. One of these is based on Berkley Distribution of UNIX (BSD) and the other is AT&T System V. The file system layout of HP-UX version 10.x and above is based on AT&T system V release 4 (SVR4). The directory structure starts with the root directory. All other directories are named relative to the root directory. There are two major groups of these directories. One is the group in which system files are present and don't change frequently. This is the static part of the directory hierarchy. The other group contains those files and directories that are changed on a routine basis and are sometimes called dynamic files and directories. An example of this type of file is log files that change on a day-to-day basis. Another division of directories may also be based on shared and nonshared files.

Architecture

The essential core of the UNIX system is the kernel, which provides facilities ...