What is a Command Line Interpreter? Generally, all modern programs have a Graphical User Interface (GUI) . This means that the interface has menus and buttons that the users can use to interact with the system. But a command-line interpreter is a program that accepts only text commands from a keyboard. These commands are then executed to the operating system. The lines of text that the user enters from the keyboard are converted to functions that the OS can understand. This is the job of the command line interpreter.

Command-line interpreters were widely used until the 1970s. Later, they got replaced by programs with Graphical User Interface.

Where are Command Line Interpreters used?

One common question that people have is, why would anyone use a command-line interpreter today? We now have applications with GUI that have simplified the way we interact with systems. So why type out the commands on a CLI? There are three important reasons why command-line interpreters are still relevant today. Let us discuss the reasons one by one.

  1. Certain actions can be done more quickly and automatically using the command line. For instance, the command to shut down some programs when a user logs in or the command to copy files of the same format from a folder can be automated. This will reduce the manual work from your side. Thus for quick execution or to automate certain actions, commands are given from the command line interpreter.
  2. A graphical application is quite easy to use. It is not only interactive but also self-explanatory. Once you download the application, there are a bunch of menus/buttons, etc… that will guide you with any operation within the program. Thus, new, and inexperienced users always prefer using a graphical application. Using a command-line interpreter is not as simple. There are no menus. Everything needs to be typed out. Yet, certain experienced users use the command line interpreter. This is mainly because, with a CLI, you have direct access to functions in the operating system. Experienced users know how powerful it is to have access to these functions. Thus, they make use of the CLI.
  3. Sometimes, the GUI software on your system is not built to support the commands needed to run or control the operating system. At such times, the user has no option but to make use of the command-line interface. If a system lacks the resources needed to run a graphical program, then Command Line Interface comes handy.

In certain situations, it is more efficient to use Command Line Interface over a graphical program. The primary purposes of using a CLI are listed below.

  • In command-line interpreters, it is possible to display the instructions using the Braille system . This is helpful for blind users. They cannot make use of graphical applications independently as the interface is not user friendly for them.
  • Scientists, technical experts, and engineers prefer command interpreters over graphical interfaces. This is due to the speed and efficiency with which certain commands can be executed.
  • Certain computers do not have the resources needed to support the smooth functioning of graphical applications and programs. Command-line interpreters can be used in such cases as well.
  • Typing commands can be accomplished faster than clicking on the options in a graphical interface. A command-line interpreter also provides the user with a wide range of commands and operations that are not possible with a GUI application.

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What are some instances where command-line interpreters are used in the modern-day?

There was a time when typing out commands was the only way to interact with the system. However, with time, graphical interfaces became more popular. But command line interpreters are still in use. Go through the list below, to know where they are used.

  • Windows OS has a CLI called Windows Command Prompt.
  • The configuration of Junos and Cisco IOS routers is done using command-line interpreters.
  • Some Linux systems also have the CLI. It is known as the Unix shell.
  • Ruby and PHP have a command shell for interactive use. The shell in PHP is known as PHP-CLI.

Are all command-line interpreters the same?

We have seen that a command interpreter is nothing but a way to interact with the system with text-based commands only. While there are several command-line interpreters, are all of them alike? No. This is because the commands you type in the CLI are based on the syntax of the programming language you are using. Thus, a command that works on a CLI on one system may not work the same way in other systems. You may have to modify the command based on the syntax for the operating system and programming language on that system.

It is important to be aware of the syntax and the right commands. For instance, on one platform, the command scan now would direct the system o scan for viruses. However, the same command may not necessarily be recognized in other systems. Sometimes, a different OS/programming language has a similar command. It may lead to the system performing the action the similar command would do, leading to undesirable results.

Syntax and case sensitiveness must also be considered. If you enter a command with the wrong syntax, the system may end up misinterpreting the command. The result is, either the intended action is not performed, or some other activity takes place.

Command Line interpreters in different operating systems

To perform activities such as troubleshooting and system repair, there is a tool called Recovery Console in Windows XP and Windows 2000. This tool doubles up as the command line interpreter as well.

The CLI in MacOS is called Terminal.

Windows operating system has an application called Command Prompt. This is the primary CLI in Windows. The latest versions of Windows have another CLI – the Windows PowerShell . This CLI is more advanced than the Command Prompt. Both are available in the new version of the Windows OS.

Certain applications have both – a CLI and a graphical interface. In these applications, the CLI has features that are not supported by the graphical interface. The CLI provides extra features because it has raw access to application files.

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The Command Prompt in Windows 10

Troubleshooting would be much easier if you are aware of the Command Prompt commands. Command Prompt is the name given to the CLI in Windows operating system. It is not possible or necessary to know all the commands. Here we have put together a list of some of the important commands.

  • Ping – This is a command used to check whether your local network system is working properly. If you want to know if there is an actual issue with the internet or some software causing the issue, use Ping. You can ping a search engine or your remote server. If you receive a response, it means that there is a connection.
  • IPConfig – This command is used for troubleshooting when the user is facing network issues. When you run the command, it returns details about your PC and local network. Details such as the state of different network connections, the system in use, the IP address of the router in use, etc are displayed.
  • Help – This is probably the most helpful and most used Command Prompt command. Executing this command will display the entire list of all commands on Command Prompt. If you want to know more about any particular command on the list, you can do so by typing – <command name> /? This command will display detailed information about the command specified.
  • Dir – This is used to browse the file system on your computer. The command will list all the files and folders found in your current folder. It can also be used as a search tool. Just add an /S to the command and type what you are looking for.
  • Cls – If you are screen is filled with too many commands, run this command to clear the screen.
  • SFC – Here, SFC stands for System File Checker. SFC/Scannow is used to check if any system files have errors. If repairing them is possible, that is done as well. Since the entire system has to be scanned, this command may take some time.
  • Tasklist – If you want to take a look at all the tasks that are currently active on your system, you may use this command. While this command only lists down all the tasks that are operating, you can also obtain additional information by using -m with the command. If you find some unnecessary tasks, you can force stop them by using the command Taskkill.
  • Netstat – This is used to obtain information related to the network your PC is in. Details such as ethernet statistics, IP routing table, TCP connections, the ports in use, etc… are displayed.
  • Exit – This command is used to exit the command prompt.
  • Assoc – This is used to view the file extension and even change the file associations. If you type assoc [.ext] where .ext is the file extension, you will get information about the extension. For example, if the entered extension is .png, it will tell you that it is an image file. File associations can be changed too. Consider the example assoc .log = txt file. This will make sure that all log files are henceforth considered as text files.
  • Cipher – It is used to view and change encryption details in your files and folders. You can apply some additional parameters and encrypt your files or create a new set of encryption keys. You can also search for encrypted files on your system.

Summary

  • Command Line interface is a way to interact with the system through text-based commands
  • Each OS will have its command-line interface. Thus the syntax and commands vary from system to system
  • Although CLI was once the primary mode of interaction, it has now largely been replaced by graphical interfaces
  • However, there are still certain operations that are quicker and more efficient when executed on a command-line interface. Thus, they are still in use
  • Experienced users make use of CLI to automate commands or perform some operations that are not supported by GUI programs
  • CLI is also useful for blind users
  • Basic knowledge of commands would help you with troubleshooting errors on your system