DAY 10

Notes ~

repl.it ~ > a website where one can work over any platform , and over any programming language
Virtual Box reads resource information from OS
Virtual Box creates a new Hardware from the resources available free in your system
time required to create an OS using docker is 1.2 sec(maximum)
PAS - > Platform as a Service
every 3 years a new Redhat OS is launched
Backend project of redhat is Fedora that is fedora is developed for 3 years which after completion is produced with name Redhat
Fedora is more powerful then Redhat
in a terminal , by default bash is always running
Spotify is based on docker- a containerised application
open blog - > slashdevops and search for docker
if a command is run in /etc/profile it will run always when a user is logged in

$ tac file-name.txt # reverse the order of reading from bottom to top
$ rev file-name.txt # reverse the words in file reading from top to bottom
$ qrencode -s 16x16 -o file-name.png web-site-link # Creates a QR code for the websites, -o shows output to save
$ systemctl enable docker # start the docker each time OS
$ systemctl start docker # initiate docker
$ docker ps # shows running iso file
$ docker ps -a # shows all containers running or shut-down
$ docker ps -qa # shows all id's of all pre-made containers
$ docker rm $(docker ps -qa) # delete all the containers
$ docker tag old-iso-name new-iso-name # make a copy of old-iso image with a new name with same id
$ docker rmi docker-image-tag # removes the docker image with tag provided
$ docker inspect elated_yonath # gives details about docker from which we can get ip

           [ Docker]
         [   RHEL    ]    
        [   Hardware  ]

it runs an OS for some dedicated purpose like running only Python that is running an micro Service
Docker is like a ship with containers of OS
the base OS doesn't know or have no information about the OS installed in containers.
Each container has its own IP, MAC to connect with outside world.
It is a technology provider
it works on GO language
search OS iso in hub.docker.com or run Command

$ docker search technology-name

$ docker pull image-name

$ docker images

$ docker run -it fedora
# it stand for interactive terminal

$ docker run -it --name some-name docker-image-name process-to-run

$ docker ps -a

$ docker attach container-name

  $ docker exec -it docker-container-name process-name

in backend , it talks to the kernel of based OS and creates a new container with OS of given image which contains all those micro services that you need to work with
after work completion , the container shutdowns itself
Docker is an application oriented system - > as soon as the application for which container was created is closed the container also shutdowns itself
Single process oriented system - > no more then one process can run on this container
RUN - > create a new container from docker images

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