TECH SOLUTION

TECH SOLUTION

Saturday, 19 October 2013

LINUX FILE STSTEM



FILE SYSTEM
File System Structure


1.   Red Hat has chosen to follow the standards outlined in the File system Hierarchy Standard (FHS).

2.     The FHS provides specific requirements for the placement of files in the directory structure and placement is based on the type of information contained in the file.

3.     Basically two categories of file information exist: shareable or unshareable, and variable or static.

4.     Shareable files are files that can be accessed by other hosts, and unshareable files can be accessed only by the local system.

5.     Variable files contain information that can change at any time on their own, without anyone actually changing the file. A log file is an example of such a file. A static file contains information that does not change unless a user changes it. Program documentation and binary files are examples of static files.

6.     Linux’s method of mounting its file systems in a flat, logical, hierarchical method has advantages over the file system mounting method used by Windows.

7.     Linux references everything relative to the root file system point /, whereas Windows has a different root mount point for every drive.

8.     If you have a /usr partition that fills up in Linux, you can create another file system called /usr/local and move your /usr/local data from /usr to the new file system definition.

9.     This practice frees up space on the /usr partition, and is an easy way to bring your system back up to a fully functional state.

10. This trick wouldn’t work on a Windows machine, because Windows maps its file locations to static device disk definitions.

11. You would have to change programs’ file references from c:\ to d:\, and so forth. Linux’s file system management is another good reason to use Linux on your production servers instead of Windows.



The / directory

1)     The / directory is called the root directory and is typically at the top of the file system structure.

2)     In many systems, the / directory is the only partition on the system and all other directories are mounted under it.

3)     The primary purpose of the / directory is booting the system, and to correct any problems that might be preventing the system from booting.

4)     According to the FHS, the / directory must contain, or have links to, the following directories:

i)       bin — This directory contains command files for use by the system administrator or other users. The bin directory can not contain subdirectories.

ii)    boot — On Red Hat systems, this is the directory containing the kernel, the core of the operating system. Also in this directory are files related to booting the system, such as the bootloader.

iii)  dev — This directory contains files with information about devices, either hardware or software devices, on the system.

iv)   etc — This directory and its subdirectories contain most of the system configuration files. If you have the X Window System installed on your system, the X11 subdirectory is located here. Networking related files are in the subdirectory sysconfig. Another subdirectory of etc is the skel directory, which is used to create files in users’ home directories when the users are created.

v)     home — This directory contains the directories of users on the system. Subdirectories of home will be named for the user to whom they belong.

vi)   lib — The shared system files and kernel modules are contained in this directory and its subdirectories.

vii)mnt — This directory is the location of the mount point for temporary file systems, such as a floppy or CD.

viii) opt — This directory and its subdirectories are often used to hold applications installed on the system.

ix)  proc — Information about system processes is included in this directory.

x)     sbin — Contained in this directory are system binaries used by the system administrator or the root user.

xi)  tmp — This directory contains temporary files used by the system.

xii)            usr — This directory is often mounted on its own partition. It contains shareable, read-only data. Subdirectories can be used for applications, typically under /usr/local.

var — Subdirectories and files under var contain variable information, such as system logs and print queues

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