UNIX (1)
What is Unix?
The UNIX operating system is a set of programs that act as a link between the computer and the user.
Unix is multi-user and multi-program OS.
Most versions of UNIX are open source/free.
Where do BAs have to use Unix
Primarily for investigation – testing, defect analysis.
Enter data through the GUI or CLI, but access the webserver using Unix commands to check what happened behind the stage.
BAs do not need to write code to develop the software, just understand fundamentals of Unix, know a few commands, and the ability to access the shell to open files and view/modify contents for testing purposes
What is an operating system?
An operating system (OS) is a collection of software that manages computer hardware resources and provides common services for computer programs.
makes it easy for different applications/software to use resources such as
Memory, files, keyboard, speaker, mouse, user input processing, and command/logic processing
What are the four main hardware components of an operating System? Explain in detail
CPU -
RAM
GPU
INPUT/OUTPUT buses
What does the ls function do. Speak on all variations of this function.
•ls: List files and folders in the current folder
•ls -l: List files and folders in the current folder with additional details
•ls -a: shows hidden files in the current folder
What functions show the date and time.
•date: show current date and time
•cal: show this month’s calendar
What are Bits and Bytes
A unique language of bits and bytes made up of 0s and 1s.
One “byte” means 8 “bits”
What are the four main hardware components of an operating System? Explain in detail
CPU - Central processing unit. The CPU is the brains of the computer where most calculations take place. In terms of computing power, the CPU is the most important element of a computer system.
RAM - Random Access Memory. It is a hardware device that allows information to be stored and retrieved on a computer. Because information is accessed randomly instead of sequentially like it is on a CD or hard drive, the computer can access the data much faster. However if the computer is turned off, all data contained in RAM is lost.
GUI - Graphical User Interface. The graphical user interface is a form of user interface that allows users to interact with electronic devices through graphical icons and visual indicators such as secondary notation, instead of text-based user interfaces
Input/Output Buses - The input/output bus is the pathway used for input and output devices to communicate with the computer processor. Transfer bits and bytes.
This function is used to show the current directory.
What is PWD?
: Present Working Directory
This function species the user
What is whoami?
(who you are logged in as)
What does the function cd do? Explain all variations.
•cd: Change to home directory
•cd /: Change to root directory
•cd .. : Change to parent directory
•cd dir: Change to <directory name>
This function allows us to make a new directory.
What is mkdir?
What is the Shell
Shell is a User Interface (UI) for accessing an Operating System’s services.
In general, operating system shells use a command-line interface (CLI) or graphical user interface (GUI).
CLI shells allow some operations to be performed faster in some situations, especially when a proper GUI has not been or cannot be created.
Graphical shells have a low learning curve to start using a computer, and they are simple and easy to use.
The shell is a command line interpreter; it translates commands entered by the user and converts them into a language that is understood by the kernel.
What are the three main parts of the Unix operating system. Define them in detail.
KERNEL -
Kernel is a computer program that manages input/output requests from software, and translates them into data processing instructions for the central processing unit and other electronic components of a computer.
The computer program that allocates the system resources and coordinates all the details of the computer's internals is called the Operating System or Kernel
SHELL -
Shell is a User Interface (UI) for accessing an Operating System’s services.
In general, operating system shells use a command-line interface (CLI) or graphical user interface (GUI).
CLI shells allow some operations to be performed faster in some situations, especially when a proper GUI has not been or cannot be created.
Graphical shells have a low learning curve to start using a computer, and they are simple and easy to use.
Programs - A computer program is a collection of instructions that performs a specific task when executed by a computer.
What does rm do? Explain all uses.
•rm file: Removes <file name>
•rmdir dir: Removes <directory>
What are Files? Give examples of some files.
A file is a collection of data. They are created by users using text editors.
•A document (report, essay etc.)
•The text of a program written in some programming language
•Instructions comprehensible directly to the machine and incomprehensible to a casual user, for example, a collection of binary digits (an executable or binary file);
•A directory, containing information about its contents, which may be a mixture of other directories (sub-directories) and ordinary files.
Ameya is running some Syntax on his brand new 1994 windows computer. He wants a function that will show the complete contents of a file he is using? Which function should he use?
What is less?
Warren is getting ready to take part in a 20-person League of Legends tournament and wants to know about the top and bottom 10 players participating . If he has access to the list of players which function would show him the top players on the list? Also, which would show him the bottom ten?
head file: Head shows the first 10 lines of the file
tail file: Tail shows the last 10 lines of the file
What style are Unix files grouped in? Go in detail.
All the files are grouped together in the directory structure. The file-system is arranged in a hierarchical structure, like an inverted tree. The top of the hierarchy is traditionally called “root”.