Unix is a CUI operating system. Operating system is an interface between hardware and applications software. It serves as the operating system for all types of computers, including single-user personel computer and engineering work stations etc . Approxmately 25+ millon computers now running on UNIX.

Features of Unix:

  1. Multi user capability
  2. Multi tasking capability
  3. Programming Facility
  4. Portability
  5. Communication
  6. Security
  7. Open System
  8. System Calls
  9. Help Facility


  1. Multi user: Multi user operating system means more than one user can share the same system resources .. i.e Hard disk, memory, printer, …. etc
  2. Multi tasking: Another important feature of unix is that it is Multi tasking, it is capable of carrying out more than one job at the same time. For example, it allows you to type in a program in its editor while it simultaneously executes some other command you performed in the back ground. While in the foreground you use editor, or you take a directory listing or whatever else ..

depending on the priority of the task, the operating system appropriately allots small time slots to each foregroung and back ground tasks.

  1. Programming Facility: Unix OS provides shell. Shell works like a programming language. It provides commands and keywords.By running these two user can prepare efficient programs.
  2. Portability: main reason for the universal popularity of unix is that it can be ported to any computer system.It works with 8088 processor to super computer.
  3. Communication: Unix provides the electronic mail, the communication may be with in the network of a single main computer or between two / more computer networks. User can easily exchange mail, data, programs thru such networks.
  4. Security: UNIX provides 3 levels of security to protect data. The first one is provided by assigning the passwords and login names to individual users, that ensures not any body can come and have access to your work.At the file level, there are read, write and execute permissions to each file which decide who can access a particular file, who can modify it and who can execute it.There is a file encryption, this utility encodes your file into an unreadable format, so that even if some one succeedes opening it, your secrets are safe.
  5. Open system: The source code for the UNIX system not just the executable code, it has been made available to users and programmers. Because of this anybody can adopt the unix system in different ways.this openness led to the introduction of a wide range of new features and versions customized to meet the user needs.
  6. System Calls: programs intract with kernel with system calls. Systemcalls tell the kernal to carry out various tasks for the program, i.e opening a file, writing to a file, obtaining information about a file, executing a program, terminating the process … so on.
  7. Help facility: unix provides mannual pages for unix commands


Difference between UNIX and WINDOWS servers


UNIX is multi user OS Windows is a multi user OS
UNIX is multi tasking OS Multi tasking OS
2 MB RAM is enough to boot the UNIX OS 12 MB RAM is required to boot the windows OS
Unix is processed based Windows is process thread based concept
For every user request it creates new process For number of users request it creates only one process.
Any user process is killed it will not effetc the other users It affects all users.
There is no limit for number of users working with the server Limited number of users.
It is an open system It is an closed system
Portable OS Not portable
Unix provides the programming facility No programming facility
UNIX is CUI Windows is GUI
UNIX is not user friendly It is user friendly
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