What is Linux?
Linux is a free and open-source operating system that was developed in the early 1990s by Linus Torvalds. It is based on the Unix operating system and has become a popular choice for both personal and enterprise use due to its stability, security, and flexibility.
Linux Architecture
Hardware layer:- Linux operating system contains a hardware layer that consists of several peripheral devices like a Monitor, Keyboard, CPU, HDD, and RAM.
Kernel Layer:-
The Linux kernel is the core component of the Linux operating system. It serves as the bridge between the hardware and the software, enabling communication and coordination between the two.
The kernel manages system resources, handles hardware devices, and provides various essential services to applications and other parts of the operating system.
Shell:- The shell is a program that provides an interface for users to enter commands, which are then interpreted and executed by the operating system. It is an essential tool for working with the system directly, performing various tasks, and automating repetitive tasks through scripts.
Applications:- This is the topmost layer of the Linux architecture and consists of the various applications that run on the operating system. These can be anything from productivity software and games to web browsers and media players.
Basic Linux commands
Listing commands
ls option_flag arguments --> list the subdirectories and files available in the present directory
Examples:
ls -l--> list the files and directories in long list format with extra information
ls -a--> list all including hidden files and directory
ls *.sh--> list all the files having .sh extension.ls -i--> list the files and directories with index numbers inodes
ls -d */--> list only directories.
Directory commands
pwd--> print work directory. Gives the present working directory.cd <path_to_directory>--> change directory to the provided pathcd ~or justcd--> change directory to the home directory
cd ---> Go to the last working directory.cd ..--> change directory to one step back.cd ../..--> Change directory to 2 levels back.mkdir <directoryName>--> to make a directory in a specific location
Examples
mkdir newFolder # make a new folder 'newFolder'
mkdir .90daysofdevops # make a hidden directory (also . before a file to make it hidden)
mkdir A B C D #make multiple directories at the same time
mkdir /home/user/Mydirectory #make a new folder in a specific location
mkdir -p A/B/C/D/E # make a nested directory
