DevOps Series-Day2- Become Linux Pro

Pre-requisites:

Oracle VM VirtualBox

Download Iso Image of CentOS 7

About Linux OS

• Just like Windows, iOS, and Mac OS, Linux is an operating system. 
• An operating system is a software that manages all of the hardware resources associated with your desktop or laptop. To put it simply, the operating system manages the communication between your software and your hardware. Without the operating system (OS), the software wouldn’t function.
• It is an open-source operating system. The source code of Linux is easily available to everyone.
• Linux provides security.
• Customizations are possible in Linux.
• Free to use.
• The cost of Linux is low.
• Has large community support.

Boot Processing

BIOS: Basic Input/output system executes MBR

MBR: Master Boot Record executes GRUB

GRUB: Grand Unified Bootloader executes the kernel

KERNEL: Kernel executes init/sbin

INIT Init executes run-level programs

runlevel Run level programs execute from /etc/RC

Different shells we used in Linux

• Bash shell
• Tcsh shell
• Ksh shell
• Zsh shell
• Fish shell

Some of the basic Linux commands

1. cd  Change directory
2. ls  listing of files/directory
3. ls -l long listing of files/directory 
4. echo used of reading
5. chmod change directory
6. PWD present working directory
7. uptime to display information about uptime
8. df -h disk utilization
9. du -sh disk usage
10. rm:  to remove a file

File permission in Linux

File permission in Linux is associated with three categories users, group and others 

-rw-r--r--

Different file permission associated are 

r read  4

w write 2

x execute 1 

4+2+1 = 7

For example 

1. permission 777 signifies that

       user, group, and others have all permissions i.e read write and execute

  2. permission 467 represents

      

      user has read the permission

      group has read and read and write permission

      others have all read, write and execute permission

Package manager

Yum vs APT

Yum is used with the RedHat family

APT is used with the ubuntu family

Both are used as dependency manager used to update, download and install software and packages into the system.

Thanks for reading

Tripura Kant