System Data Files And Information In Unix

The password file etc passwd and the group file etc group are two files that are frequently used by various programs.

System data files and information in unix. The unix system s password file called the user database by posix 1 contains the fields shown in the. In this tutorial you look at working with ordinary files. As in other operating systems the filesystem provides information storage and retrieval and one of several forms of. Unix uses a hierarchical file system structure much like an upside down tree with root at the base of the file system and all other directories spreading from there.

Ordinary files an ordinary file is a file on the system that contains data text or program instructions. Root has a user id of 0 superuser. System data files and information password file. The c drive and drive letters are gone replaced by a and cryptic sounding directories most of which have three letter names.

Unix file system is a logical method of organizing and storing large amounts of information in a way that makes it easy to manage. All files are organized into directories. Directories directories store both special and ordinary files. All data in unix is organized into files.

Directories are arranged in a tree1 structure. If you re coming from windows the linux file system structure can seem particularly alien. In unix and operating systems inspired by it the file system is considered a central component of the operating system. A unix system requires numerous data files for normal operation.

It was also one of the first parts of the system to be designed and implemented by ken thompson in the first experimental version of unix dated 1969. Directories are files that contain information on how to find other files. I have seen many new linux system administrator without any clue about the file system. A unix filesystem is a collection of files and directories that has the following properties it has a root directory that contains other files and directories.

A conceptual understanding of the file system especially data structure and related terms will help you become a successful system administrator. The filesystem hierarchy standard fhs defines the structure of file systems on linux and other unix like operating systems. Different disks machines may have different filesystems and we need a way of accessing files located on different disks. For example the password file is used every time a user logs in to a unix system and every time someone executes an ls l command.

In unix there are three basic types of files. The encrypted password is a copy of the user s password that has been put through a one way encryption. The conceptual knowledge can be applied to restore the file system in an emergency situation. The unix system s password file called the user database by posix 1 contains the following fields.

1 1 file system structure files have no structure at all they are only flat sequences of bytes.