The Unix OS offers several salient features, the 5 important of which are discussed below.
- Multiuser Capability
- Multitasking Capability
In a multi-user user system, the same computer resources – hard disk, memory etc. -are accessible to many users. Each has been given different terminals to operate from. All the terminals are connected to the main computer whose resources are available to all users. So, the user at any of the terminals can use not only the computer but also any peripherals that may be attached, say for instance a printer.
The following figure shows a typical Unix Setup.
At the heart of Unix installation is the host machine, often know as a server or a console. The number of terminals that can be connected to the host machine depends on the number of ports that are present in its controller card.
Several types of terminals that can be attached to the host machine are:-
Consist of keyboard and display unit with no memory or disk of its own.
PC has its own microprocessor, memory and disk drives, it is connected to host via cable and running a software on this PC we can emulate it to work as if it is a dumb terminal.
These terminals use a telephone line to connect to the host.
implying that it is capable of carrying out more than one job at the same time. It allows you to type in a program in its editor while it simultaneously executes some other commands you might have given earlier, say to sort and copy a huge file.
Note: Multitasking of Unix is different from DOS which does not give time-slices to running programs. And if there are 5 programs running in DOS and even one goes haywire, the entire machine hangs. In Unix, this is not happening.
Unix has excellent provision for communicating with fellow users. The communication may be within the network of a single main computer, or between two or more such computer networks.
Unix has three inherent provisions for protecting data.
First provided by assigning passwords and login names to individual users. Secondly, at a file level, there are read, write and execute permissions to each file to each user. Thirdly File encryption.
One of the main reasons for the universal popularity of Unix is that it can be ported to almost any computer system, with only the bare minimum of adaptions to suit the given computer architecture.