What is UNIX?
The UNIX operating
system is a set of programs that act as a link between the computer and the
user.
The computer programs
that allocate the system resources and coordinate all the details of the
computer's internals is called the operating system or kernel.
Users communicate
with the kernel through a program known as the shell. The shell is a command
line interpreter; it translates commands entered by the user and converts them
into a language that is understood by the kernel.
Features of UNIX
·
Multiuser Capability
·
Multitasking Capability
·
Communication
·
Security
·
Portability
MULTI USER CAPABILITY:
UNIX
Operating System supports many users to use the resources from different computers
connected to it at the same time. There need not be operating system installed
on all of them. A single computer with UNIX operating system can help in
running all of them at the same time.
MULTI TASKING CAPABILITY:
It
is capable of carrying out more than one job at the same time. It allows user
to type in a program in its editor while it simultaneously
executes some other commands like sort, copy a
huge file.
The
later job is performed in the background while in the foreground uses the
editor or takes a directory listing or anything else.
This
is managed by dividing the CPU time intelligently
between all process being carried out .Depending on the priority of the
task, the OS approximately allots small
time slots (of the order of milliseconds or
microseconds) to each foreground and background task.
COMMUNICATION:
The
communication may be within the network of a single main computer or
between two or more such computer networks. The users can easily
exchange mail, data programs
through such networks. Distance posses no barrier to
passing information or messages to and fro.
SECURITY:
Unix
has 3 inbuilt features for protecting data:-
i) Assign passwords and login name to users area.
ii) Provide read, write and execute permission to each file.
iii)Encrypt files into an unreadable format, and decrypting the file is also
possible.
PORTABILITY:
Unix
is a highly portable OS. It can be ported to a variety of hardware platforms.
It is the only system which has been ported across various hardware platforms
of major vendors such as IBM, DEC, HP and SUN. Most OSs are written for one
specific machine or platform only.
Advantages
of Unix
- Unix is more flexible and can be installed on many
different types of machines, including main-frame computers, supercomputers and
micro-computers.
- Unix
is more stable and does not go down as often as Windows does, therefore
requires less administration and maintenance.
- Unix
has greater built-in security and permissions features than Windows.
- Unix
possesses much greater processing power than Windows.
- Unix is the leader in serving the Web. About 90% of the
Internet relies on Unix operating systems running Apache, the world's most
widely used Web server.
-
Software upgrades from Microsoft often require the user to purchase new or more
hardware or prerequisite software. That is not the case with Unix.
Disadvantages
of Unix:
Interface
·
The traditional
interface for the Unix operating system is command line based, and this command
line shell interface may be hostile to the casual user. Unix was developed for
use by programmers and serious computer users rather than casual users. A
graphical user interface (GUI) is also available, but the traditional Unix
interface is command line only.
Special Commands
·
Commands required by
the command line interface often make use of cryptic naming schemes, and do not
give much information to notify a user of what they are doing. Many commands in
the Unix interface require the use of special characters. Small, normally
insignificant typos can have much greater effects and unexpected results on
Unix machines.
Not User-Friendly:
·
Not as user-friendly or easy
to learn for the average person as windows is.
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