Module 2 - 04-3 Flashcards
The shell
Define Shell
It is the command-line interpreter.
It helps you communicate with the operating system through the command line.
This is essentially the shell.
The shell provides the command-line interface for you to interact with the OS.
To tell the OS what to do, you enter commands into this interface.
The shell communicates with the kernel to execute these commands.
The operating system helps humans and computers speak with each other.
The shell is the part of the OS that allows you to do this.
Think of this as a very helpful language interpreter between you and your system.
Since you do not speak computer language or binary, you can’t directly communicate with your system.
This is where the shell comes in to help you.
Your OS doesn’t need the shell for most of its work, but it is an interface between you and what your system can offer.
It allows you to perform math, run tests, and execute applications.
More importantly, it allows you to combine these operations and connect applications to each other to perform complex and automated tasks.
You can think of a shell as a translator between you and the computer system.
Shells allow you to give commands to the computer and receive responses from it.
When you enter a command into a shell, the shell executes many internal processes to interpret your command, send it to the kernel, and return your results.
Define Command
An instruction telling the computer to do something
What is the purpose of the shell?
- It instructs the computer to do something.
- It organizes data.
- It activates the Linux operating system.
- It helps humans and computers communicate with each other.
It helps humans and computers communicate with each other.
The shell helps humans and computers communicate with each other. It is the command-line interpreter and helps humans communicate with the operating system through the command line.
What are some different types of Linux shells (5)?
- Bourne-Again Shell (bash)
- C Shell (csh)
- Korn Shell (ksh)
- Enhanced C shell (tcsh)
- Z Shell (zsh)
What does bash stand for?
Bourne-Again Shell (bash)
It uses the dollar sign ($) to indicate where users type in their commands
What does csh stand for?
C Shell (csh)
What does ksh stand for?
Korn Shell (ksh)
It uses the dollar sign ($) to indicate where users type in their commands
What does tcsh stand for?
Enhanced C shell (tcsh)
What does zsh stand for?
Z Shell (zsh)
It uses the percent sign (%) to indicate where users type in their commands
Explain Bash
Bash is the default shell in most Linux distributions.
It’s considered a user-friendly shell.
You can use bash for basic Linux commands as well as larger projects.
Bash is also the most popular shell in the cybersecurity profession.
What commands can the shell take?
- Standard Input
- Standard Output
- Standard Error
Communication with the shell can only go in one of three ways: the system receives a command—this is input; the system responds to the command and produces output; and finally, the system doesn’t know how to respond, resulting in an error.
Define Standard input
It is the information received by the OS via the command line.
The information is input from your keyboard to the shell.
If the shell can interpret your request, it asks the kernel for the resources it needs to execute the related task.
Define Echo
A Linux command that outputs a specified string of text
Define String data
Data consisting of an ordered sequence of characters
Define Standard output
It is the information returned by the OS through the shell.
Output is a computer’s response to the command you input.
Output is what you receive.
