The Concept of a Command-Line Interface - Essay Example

Running Head: The role of the CLI in modern computing operating systems The role of the CLI in modern computing operating systems Type hereUniveristy name Date Introduction to Command line interface A Command-line interface means a method through which we can interact with the operating system of a computer by typing commands in order to perform certain work. This is opposite to the interface we are used to, which is the Graphical User Interface ( GUI) that we mostly use with the help of a mouse and click on icons, menus, and folders. In a CLI, we enter commands for a computer to perform specific tasks. The system waits till the user to press ‘enter’ command to understand that the user has finished entering the command and now he can start executing it. A CLI comes with a command line interpreter that interprets the command and implements it. The command line interpreter might be running in a text terminal or in a terminal emulator windows as a remote shell. Once the command finishes execution, the output of that command might be in the form of a text displayed on the interface itself (MSCOM, 2007). The concept of CLI emerged when teletypewriter machines used to connected to computers in 1950s, and gave results on the demand as compared to other technologies such as batch based punched card inputs used during those times. After the success of the initial CLIs, next came the CRT based terminals that had the capability of interacting faster, they could display more information, and the development kept on going. Currently, the personal computers of today have all three forms of processing, i.e. batch processing, GUI and CLI. CLIs are complex, and most non-computer people prefer not to use it. This is why, it is often assumed that CLIs have become extinct and they are no longer used. However, it is not the case as CLIs continue to grow alongside the GUIs provided by Microsoft Windows, Mac OS, Linux, etc. Several application also utilize the CLI and mix it with GUI to achieve better results. An example of such application software is MATLAB, and AutoCAD. Besides being embedded with different applications, all the operating systems implemented on the routers, switches, etc. for networking have CLI based operating systems. Application of CLI The application of CLI is when we have a large number of commands or queries available along with different options and we can give those commands faster than we can using a GUI. The command shells of various operating systems that come with Windows, Linux, Mac Os, etc. work on similar base. Some programming languages such as BASIC, Python, Forth, LISP, etc all provide a modified interactive version of command line interface. Another major application of CLI is its use in engineering and scientific problems by engineers, programmers, system administrators and other advanced users of computers. A CLI consists of syntax and semantics. Syntax means the grammatical rules that govern the language and all the commands must follow them. Different operating systems such as MS-DOS, Unix, define their own set of rules that the commands given in them must follow. Similarly, in systems where CLIs are embedded, for example, Juniper systems, Cisco systems, etc. they come with their own set of rules and all commands given in those CLI need to conform to that syntax. The semantics of a system are responsible for defining the sort of operations possible and the kind of data this is needed with those operations. It also specifies the way in which the grammar is supposed to represent the data and operations, their symbolic meanings. Sometimes, two CLI might have the same syntax or the semantics. However, only in the case when the syntax and semantics of both the CLIs are similar to a large extent that allows users to use both the CLIs in the same manner. They do not need to learn the semantics or the syntax to use the other one and they can also re-use their scripts. The layout of a simple CLI would be a command prompt also known as a command line that the user types and ends with the pressing of the enter key. The interpreter would execute the entered command and return the output or an error. The above mentioned procedure is the most simple and basic form of CLIs, however, with the evolution of CLIs, now they may interpret and expand the parameters of the command line before they execute the command. They might also capture and redirect the output. CLIs do not have buttons or menu items like we have in GUIs, as the command line is self-explanatory. Moreover, command lines have the flexibility of changing various defaults values and could be customized according to requirements. A MS-DOS CLI in Windows 7. CLI of Matlab Relationship between Command line interface shells and scripting A command line shell is basically a text-only window that has a fixed number of rows and columns and the shell program controls it. It has a prompt that is displayed when it ready to take commands. It does not include graphics and takes in commands line-by-line. Now, some command line shells such as UNIX come with some graphical capabilities (GUI Vs Command line interfaces, 2009). Scripts are synonymous to the ones that actors get and they perform in the way the scripts demands. Similarly, we can define scripts as set of commands typed in a command line shell to achieve a certain purpose saved into a file. Those commands are saved in a file so that the user does not have to type them again and again. This methodology works particularly well in cases where a user has to perform repetitive commands. Scripting is the process of writing scripts. The relationship between scripting and command line shells is that we implement scripts on shells. Command line shells are responsible for the execution of a single command or sets of commands. The command line interpreter reads the command entered by the user in the form of a text. It analyzes the command and if it does not have an syntactical or semantic error, it executes the command. Similarly, if a user has to perform a set of commands, he can save them in a file and the command line interpreter would execute the commands in the file. One of the most popular GUI based operating system, Windows XP comes with two interfaces for running VBscripts and Jscripts. One interface is GUI based while the other is Command line. The feasibility of command line interface is more as it comes with more options to administer the system and the default scripts that Windows come with are also easy to run in command line (Laurie, 2010). Use of CLI in networks and resource management Command line interface is mostly used in network device management. CLI enables the user to communicate with the network device management. Using CLI, the users can interact with any of the components of the computer, hardware devices, network devices, the operating system and other application. CLI founds its most prominent place in modern day computing in the form of a management tool for networks. Although, a number of network management protocols such as SNMP and TL1 exist, however, CLI is the preferred mode of interaction for a number of network devices. Moreover, as we have mentioned earlier, scripts could be used to simplify configurations carried out on CLI. Therefore, CLI is the most powerful tool for management of resources as well as networks. Once the internet and IP networks gained popularity, the CLI was offered not only on serial links but also on TCP and other such protocol so as to provide flexibility to the users so that they can use the same commands from a different remote terminal. We regard the remote and local management terminals as the Management Consoles (CLI overview, 2009). Strengths of CLI The major strength of a CLI is its speed of use, skilled users can work faster with a CLI than GUI for a number of tasks. Sometimes, GUIs tend to be inconsistent when operations and options appear differently for different users depending on different patterns of usage. It might end up annoying users as the user would have to learn the menu every time. GUIs do not offer complete access to their available options whereas in case of CLI, all options and procedures are available and could be carried out in a similar manner. CLI offer scripting functions and can batch process operations without much user intervention. GUI based scripting is mostly limited. Moreover, another advantage of CLI is that they do not use scripts for simple commands, a simple utility ‘alias’ could be used. CLI require lesser bandwidth to work with whereas GUI requires much more bandwidth. Similarly, modern CLIs use lesser system resources such as processor time and memory than the modern GUIs (Command line interface, 2010). Conclusion The evolution and intermingling of the CLI in the modern day computing and the development of newer applications taking advantage of the strengths of CLI tells us that CLI can never become obsolete. They have their own strengths, which the users can capitalize on given they understand it. A CLI helps a user to carry out perform analysis related tasks faster than with GUI. Command line interfaces provide unlimited freedom to the user to perform tasks and achieve desired results. This is a major strength of CLI. All companies such as Microsoft, Macintosh, Linux have invested in the development of Command line interfaces giving us a clear idea that command line interfaces are here to stay. References GUI Vs Command line interfaces (2009). Softpanorama. Retrieved on November 14, 2010 from < http://www.softpanorama.org/OFM/gui_vs_command_line.shtml> Laurie, Victor (2010). Running VBScript and JScript files from the Command Shell. The command line in Windows. Retrieved on November 14, 2010 from < http://commandwindows.com/scripts.htm> CLI Overview (2009). Retrieved on November 15, 2010 from < http://www.webnms.com/cagent/help/technology_used/c_cli_overview_tech.html> Command Line interface (2010). Retrieved on November 15, 2010 from < http://www.spiritus-temporis.com/command-line-interface/advantages-of-a-command-line-interface.html> MSCOM (2007). The GUI versus the Command Line: Which is better? (Part 2). 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