arsine, a custom shell command line interpreter

:a step by step process of how the custom shell, arsine, processes the input command ‘ls -l‘ and returns output in a terminal emulator Co-Authored with: Bobby Yang, follow @glyif on twitter and github. For reference to the code of arsine, it is hosted on github (@glyif , repo simple_shell): https://github.com/glyif/simple_shell These beginning steps until the custom _getline() function all occur for all processes and all inputs into arsine including ls -l, and so therefore, there is no specific explanation of what happens in the case of ls -l until the _getline() function explanations. arguments inventory The major component of the initialization of arsine occurs in a function that builds a struct termed the arguments inventory. This arguments inventory has almost all of the major variables utilized within arsine; also, many of the functions in arsine take the arguments inventory as input parameters. It was a concept that was implemented in […]

can’t see the forest through the trees

:on the kernel | linux vs. unix | operating system vs. ubuntu vs. virtual machine | shell vs. bash | command line vs. terminal As daunting as I imagined the task of writing this article would be, it wasn’t worse than the feeling I continually face of having to learn to program software without a solid grasp of the meaning of the aforementioned components and applications. I often feel confused as to the differences between each of the above listed components and systems. My main problem is that I miss the big picture of how my computer software that I utilize is structured and connected to the rest of my computer. This also creates problems for how I communicate about what I’ve coded on my computer, especially for people that use different software and different machines. Not being able to explain how I’ve been using a computer is at least unflattering and certainly […]

what the f*Lib.a?

:C language libraries, part 1, static librariescompiler: gcc (Ubuntu 4.8.4-2ubuntu1~14.04.3) 4.8.4environment: vagrant virtual machine with linux 14.04.5 LTS for Ubuntulanguage: C languageHave you been learning C language and using #include <stdio.h> and have no idea what is happening with that? If so, then this post is for you! I will be discussing C language static libraries, why to use libraries, how they work, how to create them, and how to use them. For background information on the subject, it’s helpful to understand what happens when C language files are compiled; for more information on that, check out my other blog post: Computer Compilers: brief introduction, which helps to explain how the gcc compiler works. As this is the first blog of a two part series, please refer to my other post on libraries: what the f*Lib.so? for more on dynamic libraries.In the above referenced post on computer compilers, you will see that during the gcc compiling process, the […]

computer compilers: brief introduction

:on how a compiler works, using the GNU Compiler Collection gcc as an examplecompiler: gcc (Ubuntu 4.8.4-2ubuntu1~14.04.3) 4.8.4 environment: vagrant virtual machine with linux 14.04.5 LTS for Ubuntu language: C languageIf you have begun to experiment with and learn about computer code and software languages, after the early 1980’s, it is very likely that you began using higher level languages, and much later learned about compilers. At least this is how I have begun to learn to code computer languages. I have been touching the surface of html, css, javascript, and PHP for almost 2 years, and I never knew what a compiler was. This is because these languages are interpreted by a browser or another lower-level environment instead of being compiled. The browser or other environment reads the instructions and uses its own logic and mechanisms to interpret and respond to the input codes. Did you ever wonder how a browser […]

links: hard vs. symbolic

:using the ln command in bash to distinguish between hard and symbolic linksStated below is an excerpt from the unix BSD General Commands Manual on ‘ln’. In the description, I have only copied one option, which is relevant to this tutorial, and I have left out the majority of the content from the manual. NAME: link, ln — make links SYNOPSIS: ln [-Ffhinsv] source_file [target_file] DESCRIPTION: The ln utility creates a new directory entry (linked file) which has the same modes as the original file. It is useful for maintaining multiple copies of a file in many places at once without using up storage for the “copies’’; instead, a link “points’’ to the original copy. There are two types of links; hard links and symbolic links. How a link “points’’ to a file is one of the differences between a hard and symbolic link. The options are as follows: -s […]

how the terminal works: command line input

:do you ever wonder how a computer works?As a beginner software engineering student at bootcamp School, we are being taught to use the terminal command line to use the functions of a computer. In this post I will explain a very basic concept of what happens with a computer when a user types input. In my work so far and in the ways that I explain a computer system, I will be referring to the bash shell program in Mac OS terminal using ubuntu and GNU linux (click the links for wikipedia references on those concepts).Additionally, to help with my explanation, I’ll use the input command ls *.c as an example of many of the concepts of how terminal and a computer work. This is how that command might look in your terminal:USER@computerNAME: ~/$ ls *.c To learn about commands from the manuals in terminal input ~/$ man yourcommand; an […]