session-02.txt

What is DevOps?
Linux importance
waterfall vs agile vs devops
client server architecture

AWS account creation

EC2 server launch

Authentication
---------------------
Laptop --> Username and password
		   fingerprint
		   
1. What you know
2. What you have
3. What you are

username and password --> what you know
tokens --> What you have, OTP, RSA physical token, software tokens
what you are --> fingerprint, retina scanning, palm

keys or tokens

Cloud servers are remote servers --> they are somewhere in internet

SSH --> Secure shell --> Linux authentication mechanism
port no 22

username/password
username and private-key

what are keys?
------------------
Public vs Private keys

public private key we will generate

Linux Server Launch
--------------------
Linux Torvalds
He bought one laptop
UNIX
	strictly coupled with hardware
	MAC laptop is software+hardware --> we dont have freedom to choose OS
	It is not free, high cost
DOS
	blue screen
	not free

He started writing OS from the scratch using C language
No strict couple with hardware
free
opensource

Linux is OS/Kernel?
Kernel --> it is a software component that can interact with hardware

few companies developed shell to interact with kernel and few utilities

Kernel+Shell+utilities/apps == OS

Flavours/Distributions
-----------------------
Ubuntu
Suse
IBM
Centos
Fedora
RHEL --> Redhat Enterprise Linux
Arch Linux
Android

Desktop --> graphics
Server --> No graphics only terminal/shell

enterprise --> you will have support from Redhat
opensource/community --> no support, only community support

RHEL=CentOs=Fedora=AWSLinux

Centos8

RHEL-9

EC2 Server Launch
-----------------
Public key and private keys

GitBash --> Mini Linux for windows
SSH Client, Git Client

Windows Home folder
-----------------
C:\Users\<Laptop-Username>

C:\users\user

\ --> Windows

/ --> Linux

pwd --> present working directory

ssh-keygen --> command to create pub and private key

ssh-keygen -t rsa -b 4096 -f <your-file-name>

.pub --> publickey
no extension --> private-key

.pem is for private-key

EC2 Launch
------------
create key in AWS account
Firewall creation
0-65,535 -> 65,536

Delhi --> HYD

flat no, apartment name, street, city, pincode

every process will open one port number...

https://facebook:443 --> there is a https process running inside facebook server or port no 443

a random port will be opened for this chrome tab

facebook 443, I opened a random port 44565

SSH port no 22...only facebook admin staff will have this access
facebook https access --> yes public will have this access

443 --> open for public
22 --> only open for admin staff

0.0.0.0/0 --> internet, open for everyone

CPU
RAM
Storage
OS


54.86.71.109

ssh -i <private-key> user-name@IP

ssh -i daws-78s user-name@IP

port no, ip, username/password

https://facebook.com:443

gitbash --> ssh client
putty, mobaxterm, superputty

$ --> normal user
# --> root access


/c/devops/daws-78s/daws-78s.pem --> absolute
daws-78s/daws-78s.pem --> relative

command-name <options> <inputs>

ls --> list subdirectories

/home/ec2-user --> default folder when logged in

cd --> change directory

/ root directory
/home/ec2-user

ls -l --> long format
ls -lr --> reverse alphabetical order
ls -lt --> latest files
ls -ltr --> starts from old files
ls -la --> all files and directory including hidden

CRUD --> Create Read Update Delete

ls --> read
I want to create files folder

create file
---------------
touch <file-name> --> this will create a file
update --> enter info into file
cat > sample
entr the text you want
once over click enter and ctrl+d

> --> replace old content
>> --> append/add to the old content

Delete
----------------
rm  <file-name>
rm -r --> recursive
rmdir --> deletes only empty directory, fails when it has files inside

mkdir --> make directory