Welcome to Unix world.. !!!

is a Unix-like and mostly POSIX -compliant(Unix) computer operating system assembled under the model of free and open-source software development and distribution.

Why Linux ??

•  Linux is very stable!
• Linux is easy to install!  I
• Linux is less vulnerable to computer malware
• Cost
• More software choices with more features and greater usability

     Therefore Enterprises prefer to use                                                                     Linux  

Software features.

• Most of the basic Linux utilities( is a small program that provides an addition to the capabilities provided by the operating system.) are GNU software.

•  GNU utilities support advanced features that are not found in the standard versions of BSD and UNIX System Vprogram.

• A shell is a program which reads and executes commands from the user. Many types of shells are available for Linux

                C SHell (csh)
                Bourne SHell sh
         GNU Bourne Again Shell (bash)
                 tcsh

 Hardware requirements.

• Linux is available for many platforms in addition to Intel 80x86 systems,Macintosh, Amiga, Sun SparcStation
• Linux currently supports systems with the Intel 80386, 80486, or Pentium CPU,
• require 4 megabytes of RAM at the very least, and 16 megabytes at most

Latest version of Linux released by RedHAt by November 2014 =>Red Hat Enterprise Linux 6.5

       Red Hat is an American Multinational Software Company providing Opensource software to enterprise community

Fedora Project 

Red Hat sponsors the Fedora Project, a community-supported open-source project that aims to promote the rapid progress of free and open-source software . 

Business model

Red Hat partly operates on a professional open-source business model (open code comm can develope)   

In September 2014, it was announced that  Red Hat was "in the midst of a major shift from client-server to cloud-mobile..    Client-Server => Cloud-Mobile. For that they needed to  

• position Red Hat as the provider of choice for enterprises' entire cloud infrastructure."

•    chance to establish open source as the default choice of this next era   

  Red Hat enterprise Linux 6.5

   Red Hat Enterprise Linux 6.5 is designed for those who build and manage large, complex IT projects, especially enterprises that require an open hybrid cloud. 

   Red Hat Enterprise Linux 6.5 provides the security and networking, virtualization needed to manage these environments, such as tools that aid in quickly tuning the system to run SAP applications 

  http://www.redhat.com/en/about/press-releases/red-hat-launches-latest-version-of-red-hat-enterprise-linux-6

Chapter 1. The Linux File System

  The Linux file system is a hierarchically structured tree.  

  A file system is always stored on media (be it a hard drive, a CD or a memory    fragment)

Mounting File Systems

 the root of the file system is stored in one partition and most of the time it is needed to combine many partitions to store a single file system

Combining one partition with a file system => Mounting the File System

Mounting

 the root of the file system is stored on one partition and its users' files are stored in another

here home and everything beneath that are stored in another partition same for bin, boot

The action of mounting requires to identify the location of the filesystem to mount as Mount Point (here /home is the mount point and everything below /home is stored in another location )

Partitions and Disks

Every hardware device (except the network interface) available to the Linux system is represented by a device file inside the /dev location. Partitions and disks are no exception.

The Linux File System Locations

1. System Required Locations

locations that you cannot place on another file system medium, because these locations are required by the mount command itself to function properly

• /bin  => contains executable programs needed to bring the system up and    running.
  
  
• /etc  => contains all the configuration files for the system (not the user-specific configurations)
  
• /lib  =>usually contains the system libraries necessary to successfully boot the system and run the commands which are located inside /bin.
  
  
• /sbin => contains executable programs.
                 contains programs solely for system administrative purposes
  

  2. Userland Locations

   contain the files for the regular operation of a system (such as application data and the applications themselves). 

  These can be stored on separate media if you want, but if you do, you will need to setup an initial ram disk to boot your system with.

  /usr => the root of the userland locations  

  •              /bin, /lib , /local , /share are under it.

  3. General Locations

  everything else which might be placed on a separate medium 

  • /home  => home directories of all the local users
    
  • /boot  => contains the static boot-related files, not actually necessary   once the system is booted(bootloader configuration)
    
  • /media  => contains the mount points for the various detachable storage (like USB disks, DVDs, ...)
    
    
  • /mnt  => for temporarily mounted media
    
  • /opt  => add-on packages and is usually used to install applications into which are not provided by your package manager natively (as those should reside in /usr) or build specific to the local system (/usr/local).
    
  • /tmp  => temporary files for the system tools. The location can be cleansed at boot up.
    
  • /var  => data that changes in size, such as log files, caches, etc

  Special Kernel-provided File Systems

  
  
  • /proc =>information about the running system, kernel and processes
    
  • /sys  => information about the available hardware and kernel tasks
    
  • /dev  => device files