User and Operating System Interface

User and Operating System Interface

• Various methods are used to interface with the operating system. They are command-line interface, Graphical User Interface and Touch-Screen Interface.

Command Interpreters

• A command interpreter is a system software that understands and executes commands that are entered interactively by a human or from another program. Command interpreter is an important part of any operating system. It provides an interface between the user and the computer.

• Command interpreter is also called command-line interface.

• Most operating systems, including Linux, UNIX and Windows, treat the command interpreter as a special program that is running when a process is initiated or when a user first logs on.

• A command interpreter is often also called a command shell or simply a shell. A command shell also usually provides a set of programs or utilities which allows ad users to perform file management functions.

• The shell utility provides a user interface to many system services. For example, user requests such as listing file names in a directory, running a program, logging out, may all be handled by the shell. The shell may invoke other utilities to actually do the work; for example, directory file listing is sometimes a utility program itself.

• The command interpreter itself contains the code to execute the command. For example, a command to delete a file may cause the command interpreter to jump to a section of its code that sets up the parameters and makes the appropriate system call.

• User may choose among several different shells, including the C shell, Bourne-Again shell, Korn shell, and others. Third-party shells and free user-written shells are also available. A very popular shell on most commercial variants of Unix is the Korn shell.

• Command line is text based interface of the Linux system. Terminal is another name in Linux system. User can communicate with system is by using command. You can combine more than one command and get output.

• Commands are executed at the prompt. Command line interface gives the user more control and options. There are many varieties of Linux, but almost all of them use similar commands that can be entered from a command-line interface terminal.

• The syntax of command line is as follows:

#command options

• Example :

[root@IAD~]# hostname

Here we will explain all of above arrows one by one.

1. Logged in user name, as now currently we are logged in with root user.

2. After the @ sign we have hostname of our Linux.

3. This is current working directory, "~" it is user home directory sign in Linux.

4. "#" hash sign or number sign means we are logged in with super user such as "root" it will be changed in case if we are logged in with normal Linux user e.g "$"

5. Just for example we give "hostname" command to shell, hostname is used to know the fully qualified hostname of your Linux machine.

6. This is output of our previously entered command.

Graphical User Interface

• GUI provides a graphical interface for the user to interact with the computer. It is the common user interface that includes graphical representation like buttons and Marie icons and communication can be performed by interacting with these icons rather than the usual text-based or command-based communication.

• The GUI actually translates user language, which comprises simple one-line commands, single click and double clicks to machine language or assembly language. The machine understands machine language and hence the machine responds to the task initiated, which is translated to use language and communicated to the user via GUI.

• The first commercially available GUI was called "PARC," and was developed by Xerox for its 8010 Information System, released in 1981.

• The actions in a GUI are usually performed through direct manipulation of graphical elements like buttons and icons. Communication can be performed by interacting with these icons rather than the usual text-based or command-based

communication.

• Graphical user interface applications are self-descriptive, feedback is typically immediate and visual cues encourage and steer discoverability

Touch-Screen Interface

• The first touch screen phone was launched in 1992 by IBM and was named IBM Simon. iPhone was the latest invention of the touch screen phone which gets its popularity in no time.

• Whether it is touch screen microwave, touch screen car LCD, touch screen monitor, touch screen ATMs and others. The interface of touch screen devices is made in such a way that it is easy for people to use them.

• Some touch screen interface is fully controlled by the touch screen while others are partially controlled by the screen and another function is controlled by the physical keyboard.

• A touch user interface is a type of interaction between computer-based device. This interaction is by doing a physical touch on the screen and the computer responds to this touch interaction.