Day 2: Linux Overview

How Linux Works

Linux is an operating system or kernel distributed under an open-source license. Its feature list is very similar to Unix. Unlike Unix, Linux is freely available. The kernel is a program at the heart of the Linux operating system that performs basic tasks such as hardware and software communication.

Linux Architecture

Kernel: The kernel is the core of any Linux-based operating system. It virtualizes common computer hardware resources to provide virtual resources for each process. This makes it appear that the process is the only one running on the device. The kernel is also responsible for preventing and reducing conflicts between different processes.

System Library: A special type of function that is used to implement the operation of the operating system.

Shell: This is an interface to the kernel that hides the complexity of the kernel's functionality from the user. It receives commands from the user and executes kernel functions.

Hardware layer: This layer consists of all peripheral devices such as RAM/HDD/CPU.

System Utilities: Provides operating system capabilities to the user.

Linux File System Hierarchy

Few basic Linux commands

1. Check your present working directory

    $ pwd
   

2. List all the files or directories including hidden files.

    $ ls -la
   

   ls -l--> list the files and directories in long list format with extra information

   ls -a --> list all including hidden files and directories.

   ls -la --> list all including hidden files and directories in long list format with extra information.

3. Create a nested directory A/B/C/D/E.

    $ mkdir -p A/B/C/D/E
   

   mkdir -p --> This command can create multiple directories at once as well as it will set the permission for those directories.

4. Check RAM utilization.

    $ free -h