UNIX/Linux Basics

Unix/Linux

An operating system (OS) used with shell to interact with the OS

Kernel

Main program of a Unix system that controls peripherals

Shell

Interface between the user and the kernel that interprets commands

Multi-User

Capability for many people to use one machine simultaneously

Process

A running program identified by a unique Process ID (PID)

Directory Structure

Hierarchical tree structure containing files and directories

/bin

Contains binary essentials for system operation

/home

Location of all home directories

/var

Contains frequently changing files like logs

/etc

Contains various system configuration files

/dev

Contains various devices as files, e.g., hard drives, CD-ROM drives

/sbin

Contains binaries for superuser use only

/tmp

Contains temporary files

Superuser

Special user acting as an administrator with unrestricted access

Case Sensitivity

Unix is case-sensitive, treating files with different cases as distinct

Online Manual

Extensive online manuals available for Unix

Relative Path

Position in the directory tree dependent on the current location

Absolute Path

Position in the directory tree defined uniquely regardless of current path

Redirect & Append

Using > to redirect output to a file and >> to append output to a file

Pipe

Using | to use output from one command as input for another

Permission

Files and directories have owners and permissions for different user groups

Process

A unit of a running program with unique Process ID (PID)

Foreground & Background Jobs

Jobs can run in foreground or background mode with specific commands

Vi Editor

A text editor available on most UNIX systems, working with a variety of terminals and providing a customized editing environment.

UNIX

An operating system on which Vi Editor is available and widely used.

Modes

Two modes in Vi Editor: COMMAND mode (default) and INSERT mode for entering data.

Command Mode

The default mode in Vi Editor where anything typed is interpreted as a command, and ESC is used to return to it.

Insert Mode

A mode in Vi Editor where anything typed is interpreted as data, and ESC is used to exit.

Window Positioning

Using commands like ^f, ^b, ^e, :n, G, and arrow keys to move the window and cursor within Vi Editor.

Write & Quit

To write to the file & quit the editor, use :wq; to undo the last command, use u or U.

Delete Functions

Commands like dd, x, i, a, o for deleting lines or characters and inserting data in Vi Editor.

Open Files

To open several files in Vi Editor, use the command vi file1 file2 ... to edit them simultaneously.

Search Patterns

Commands like /.../, ?...?, n, :s/.../.../ for searching, advancing, and replacing patterns in Vi Editor.

Move Text

Using commands like ma, d'a, p to mark, delete, and put text in the buffer in Vi Editor.

Copy Text

Using commands like ma, y'a, p to mark, yank, and put text in the buffer in Vi Editor.

Write to File

Commands like :w, :w filename, :w!, m,nw filename to write, overwrite, or write lines to a named file in Vi Editor.

Useful Functions

Commands like :e, :e file, :r filename, !cmd, :linenumber for re-editing, reading, executing, and navigating in Vi Editor.

More Commands

Commands like yl, yw, d^, d$, Dw for yanking characters/words and deleting text in Vi Editor.

Tailoring Environment

Using :set options, :set nu, :set all for tailoring the current session and viewing settings in Vi Editor.

C++ Basics

Fundamental concepts and syntax of the C++ programming language

Program Structure

The organization and layout of a C++ program, including functions, classes, and statements

Comment blocks

Sections of code used for documentation and ignored by the compiler

Preprocessor directives

Commands that provide instructions to the compiler before the actual compilation process

#include

Directive to load predefined code interfaces for functions, classes, and other entities

Header that loads the C++ input/output library from the default location

Header that loads the C-style standard library from the default location

Using statements

Statements that allow the use of entities from a specific namespace without specifying the namespace

Main function

The entry point of a C++ program where the execution begins

g++ Compiler

A C++ compiler that is part of the GNU Compiler Collection

Compilation

The process of translating .cpp files into .o object modules

Linking

The process of combining .o modules to create a single executable

Syntax & Behavior

The general rules and actions of using the g++ compiler

Options for g++ Compilation

Various flags and commands used during the compilation process with g++

Options for g++ Linking

Various flags and commands used during the linking process with g++

Sample g++ Commands

Examples of commands used with the g++ compiler for compilation and linking

Makefile

A GNU utility that automates the compilation and linking of program components

Makefile Lingo

Terms and concepts related to the structure and syntax of a Makefile

Layout

The structure and format of a simple makefile consisting of rules, targets, prerequisites, and commands

Prerequisites

Files needed to create the target in a makefile

clean Target

An important target in a makefile used to remove compilation products and clean up the directory

Final Product

The result of refining a makefile with variables, compile options, and comments

Makefiles in Professional Work

The use of makefiles in the industry for efficient code versioning and deployment on UNIX/Linux platforms