known as Root Directory. Linux operating system resides on two file system: the root file system known as

• 
  Operating system for several types of computer platforms, primarily INTEL based PC’s.
  
• 
  Goal has been to create a UNIX clone.
  
• 
  Free of any commercially copy righted software.
  
• 
  It has all the features of a modern fully fledged UNIX, like;
  
  1. 
     Multitasking
     
  2. 
     Multi-user
     
  3. 
     Programmable Shells
     
  4. 
     Device independence
     
  5. 
     Open system portability
     
  6. 
     Virtual memory
     
  7. 
     Shared libraries
     
  8. 
     Demand loading
     
  9. 
     Proper memory management
     
  10. 
      TCP/IP networking
      

1. 
   For Redhat Linux
   

• 
  Processor: Intel / AMD, i386 and x86_64, Pentium IV, 2.4 Ghz, 512K cache or
  Pentium IV, 2.4 Ghz dual processor, 512K cache recommended. Or above.
  
• 
  Hard Disk: 5GB.
  
• 
  Memory: 2 GB (minimum), 4 GB (recommended).
  

2. 
   For Fedora (A Red Hat Community Project).
   

• 
  Processor: Intel / AMD, i386 and x86_64, Pentium IV, 2.4 Ghz, 512K cache or
  Pentium IV, 2.4 Ghz dual processor, 512K cache recommended. Or above.
  
• 
  Hard Disk: 10GB.
  
• 
  Memory: 512 GB (minimum), 1 GB (recommended).
  

• 
  Every Linux based OS has GCC, Emacs, X—Windows all standards Unix Utilities, TCP/IP, IPX/SPX, including SLIP and PPP
  

• 
  Linux Kernel Copyright belongs to Linux Torvalds
  
• 
  Placed under GNU(General Public License) means that you may freely, copy, change and distribute it.
  

• 
  Linux is committed to the Filesystem Hierarchy Standard (FHS) a collaborative document that defines the names and locations of many files and directories.
  
• 
  Inverted tree structure, with the root at the top. The top directory, /, known as Root Directory.
  
• 
  Linux operating system resides on two file system: the root file system known as /, and a file system mounted under /usr.
  

• 
  Any program that write log files or need spool or lock directories probably should write them to the /var directory."…. This includes spool directories and files, administrative and logging data, and transient and temporary files."
  
• 
  The /var/spool directory hold data that is of transitory nature, such as mail and news that is recently received from or queued for transmission to another site.
  

• 
  The /bin directory contains executable programs, know as binaries. Many Linux commands such as ls, arch, cat, cpio etc are actually programs found in this directory.
  

• 
  The /sbin directory is also used to store system binary files. Most files (fdisk, halt, hdparm, shutdown etc.) These files are used for system administration purpose.
  

• 
  The /usr directory and its sub-directories are very important to the operation of your Linux system contains several directories with some of the most important programs.
  
• 
  Sub-directories of /usr contains large software packages.
  
• 
  The /usr directory usually has its own partition, and it should be mountable read-only.
  

• 
  The /etc directory is reserved for configuration files that are local to your machine.
  
• 
  The password file, startup scripts for Linux, list of IP addresses and many other types of configuration information stored in this directory.
  

• 
  The /lib directory should contain only those libraries that are needed to execute the binaries in /bin and /sbin.
  

• 
  The /home directory is the base for user home directories.
  

• 
  The /dev directory contains filesystem entries which represent devices that are attached to the system. These files are essential for the system to function properly. The dev/mouse file is for reading input for mouse.
  

• 
  To use the Linux operating system, you must first gain access to it by logging in. when you are log in; you are placed in your home directory.
  

• 
  login [name | option]
  

• 
  Enter your Login Name and press ENTER.
  

• 
  Enter your PASSWORD and press ENTER.
  

• 
  Once you have entered all the correct information, the “prompt character” appears on the screen. This is a dollar sign($) for Bourne shell users and a percent sign(%) for C-shell users.
  

• 
  The man command
  

Creating Directories

A directory is a collection of files. It can be thought of as a “folder” that contains many different files. Directories are given names, with which you can identify them. Furthermore, directories are maintained in a tree-like structure; that is, directories may contain other directories.

• 
  mkdir
  

Deleting Directories

• 
  rmdir
  
• 
  cd (Change Directory)
  

• 
  pwd
  

1. 
   Create multiple directories and subdirectories.
   
2. 
   Search different options of rmdir command using man command.
   

Linux Operating System of 80