The shell exposes the operating system to the user. It provides a way for a user to interact with the system and control it. A shell can have a graphical or command-line interface. In the command-line interface, a user can provide commands, scripts or other programs and execute them. For instance, you want to know the current date. You can type “date” on a terminal in your Linux, the shell will run the necessary program to show you the date. In this article, you will learn everything you need to know about shell Linux.
What is A Shell in Linux?
A shell is a program. It takes commands from the keyboard and gives them to the operating system to execute. However, nowadays most operating systems provide GUI (Graphical User Interface) to provide commands. Linux systems use a shell named bash, whereas Windows uses powershell. Command formatting can be different on different shells. Bash commands are Unix-styled and powershell commands are based on OOP (Object Oriented Programming). For instance, the “ls” command in bash performs the same task as the “Get-ChildItem” command in powershell which is listing files in the current directory. There are different types of shells available as different users have different needs and preferences.
History of Shell in Linux
The journey of shells started in the 1960s and 1970s when computers had just begun to become more than just calculators. Computer users would use different techniques to provide commands to a computer. For instance, some users would use a punch card. The cards would contain a lot of holes and the holes represented commands and data. However, those techniques weren’t user-friendly. Users were looking for a more flexible and efficient way to run commands.
In 1971, Ken Thompson introduced the first Unix shell, which is called the Thompson shell. The shell allowed users to provide commands using natural language like syntax. It was more user-friendly than previous techniques. Then Stephen Bourne developed the Bourne shell which replaced the Thomson Shell as it is more powerful and flexible. The Bourne shell is still in use today, however more advanced shells like Bash(Bourne Again Shell) have arrived later.
How Shell works
Here are the detailed steps of how the shell works
- First, the user provides a command.
- Shell divides the command into individual words.
- Shell looks for an executable file having the same name of the command in the PATH environment.
- Shell launches the program and provides necessary arguments and input.
- The program runs based on the inputs and returns an exit status at the end.
- Shell displays the output on the screen.
- Shell waits for a new command.
Types of Shell in Linux
There are different types of shells available nowadays. Here I have listed some of them:
- Bourne Shell (sh): It is used for executing basic commands and script.
- Bourne Again Shell (bash): It is the upgraded version of Bourne shell. It has features like command-line editing, job control, history Also it provides support for advanced scripting.
- C Shell (csh): It has syntax like C programming language. It also provides features like command-line editing, job control, history
- Korn Shell (ksh): It is also an improved version of Bourne shell. It also provides advanced features.
- Z shell (zsh): It includes features from Bourne, C and Korn shells. Also, it provides some advanced features like spelling correction and advanced globbing. Globbing helps to specify multiple files or directories without typing their names.
- Fish Shell (fish): It provides a more user-friendly It also includes features like text highlighting.
Command-line and Graphical Shell
Here I will talk about command-line shells and graphical shells and their differences.
A. Command-line shell
- It uses text based
- More flexible and powerful, especially in scripting.
- Require some knowledge on commands and their usage.
- Faster for working with large data sets or repetitive tasks.
- Preferable for purposes like scripting and automation.
B. Graphical Shell
- It uses graphical user interface (GUI) interaction instead of text based interaction.
- Suitable for any type of user.
- Includes drag and drop
- It provides a wide range of applications for web browsers to media players.
- It has a lot of keyboard shortcuts and GUI based features.
Terminal Vs Shell
Some people think terminal and shell are the same. But they are different from one another.
- Terminal: It can be physical or virtual. It is a text based interface which allows a user to enter commands and execute them.
- Shell: It is a program that interprets the commands and provides a way to interact with the operating system.
Advantages and Disadvantages of Shell Linux
Even though shell has a lot of advantages, it has some disadvantages as well. Here are some of the pros and cons of shell.
Advantages:
- Portable: A shell script developed in one machine can run on different machines.
- Fast: It is faster than GUI.
- Less Resource Hungry: It needs less computer resources to run whereas GUI consumes a lot of resources.
- Good for Automation and Scripting: It is more flexible, efficient and powerful for automation and scripting.
Disadvantages:
- Less Intuitive: It is less intuitive than GUI. It is hard to tell what is going on.
- Not Beginner Friendly: It requires a steep learning curve. That’s why it isn’t suitable for all types of users.
- Not as Powerful as Programming Language: Programming languages are faster than shell script. Also, programming languages provide a lot of functionality and flexibility than shell.
Conclusion
In this article, I have tried to provide you with some basic concepts on shell Linux. Hopefully, now you have a better understanding of shell Linux than before.
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