Linux and shell scripting

Most of the software professions and companies in software world are using linux based operating system.

operating system : os is used to establish connection between hardware and software

Advantages

-- Open source software

-- Secure, no need to install antivirus software like windows

-- Multiple distributions (i.e , flavours)

-- Fast

Architecture:

Kernel:

-- Heart of the operating system

-- It is responsible for device, memory, process management

-- It is responsible for handling system calls

System libraries:

--System libraries awhy we re used to perform tasks

Shell Scripting:

In OS, the way to talk to the OS is called shell scripting by using shell commands

why to use shell scripting instead of GUI?

-- In production systems, if we use GUI we need to install GUI , so the servers will become heavy, so we will make use of shell scripting

Basic commands of shell scripting

-- Connect to the ec2 instance

ls : list (used to list files and folders)

pwd : present working directory

mkdir : make directory( ex : mkdir f1)

cd : change directory

cd .. : switch back one step

cd ../.. : switch back two steps

ls -ltr : used to display files and folders list along with dates.

if the results starts with d then its a directory otherwise its a file

touch : used to create a file ( ex : touch file1)

vi file2 : is used to create the file and write anything inside it.

-- to write in it press "esc" and click i(insert mode)

-- esc and :wq! to save the file

cat : used to display contents of file

rm : remove a file

rm -r : remove a directory

free : used to see how much available space of memory etc

free -r

nproc : how many cpus are there

df -h : used to display disk size

top : monitor everything from one place( cpus, disk etc)