Linux-FileSystems

Linux File System:

The Linux file system is a hierarchical structure that organizes data and files in a tree-like format.
The root directory ("/") is the top-level directory from which all other directories and files stem.
Directories are used to organize and group files into logical categories.
Files are organized based on their type, and they can be text files, binary files, directories, device files, and more.

All Types of Directories:

Directories in Linux can be categorized as system directories (critical for system operation), user directories (for user-specific data), and temporary directories (for temporary files).
Examples of system directories include "/bin", "/etc", "/lib", "/usr", etc.
User directories like "/home/username" store user-specific data and configurations.
Temporary directories like "/tmp" hold temporary files that can be safely deleted.

VIM Editor and Its Modes:

Vim is a powerful text editor available in most Unix-like systems.
Vim has different modes: Normal mode (default mode for navigation and manipulation), Insert mode (for text input), Visual mode (for selecting text), and Command-line mode (for entering commands).
To switch from Normal mode to Insert mode, press "i". To switch back to Normal mode from Insert mode, press "Esc".
In Normal mode, you can navigate using arrow keys or "hjkl" keys, perform editing operations, and execute commands.
In Command-line mode, you can save changes with ":w", quit with ":q", and save and quit with ":wq".

How to Insert, Write, Quit in VIM:

To insert text in Vim, first switch to Insert mode by pressing "i". Then, type your text.
After inserting text, switch back to Normal mode by pressing "Esc".
To save changes, type ":w" in Normal mode and press "Enter".
To quit Vim, type ":q" in Normal mode and press "Enter".
If you want to save and quit, type ":wq" and press "Enter".

Variable Path and Actual Path in Linux:

In Linux, a "variable path" usually refers to a variable containing a directory path that can change.
An "actual path" refers to the absolute and unchanging directory path to a specific location in the file system.
For example, if you have a variable $HOME that stores the path to the user's home directory, its value might change for different users, but the actual path (e.g., "/home/username") remains fixed.

Here are the notes for the unique commands from your history, excluding the repeated ones:¶

clear: Clears the terminal screen.
logout: Logs out of the current user session.
ls /: Lists the contents of the root directory.
pwd: Prints the current working directory.
ls /home: Lists the contents of the /home directory.
touch teja.txt: Creates an empty file named teja.txt in the current directory.
vi teja.txt: Opens the teja.txt file in the Vim editor for editing.
vi ravi.txt: Attempts to open a file named ravi.txt in the Vim editor.
cat ravi.txt: Displays the contents of the ravi.txt file using cat.
cat ravi.txt: Displays the contents of the ravi.txt file again.
ls /home/: Lists the contents of the /home directory.
sudo adduser teja: Adds a user named teja using sudo.
cd /home/teja/: Changes the working directory to /home/teja.
sudo -i: Opens a new shell session with superuser privileges.
mkdir sample: Creates a directory named sample in the current directory.
touch 1 2 3 4: Creates empty files named 1, 2, 3, and 4.
mkdir -p stevejobs/apple/ios: Creates a directory structure.
ls stevejobs/: Lists the contents of the stevejobs directory.
ls stevejobs/apple/: Lists the contents of the apple directory within stevejobs.
cd ios/: Changes the current working directory to ios within apple.
touch iphone11: Creates a file named iphone11 in the ios directory.
touch /home/ubuntu/stevejobs/apple/ios/iphone12: Creates a file at the specified path.
vi /home/ubuntu/stevejobs/apple/ios/iphone12: Opens the iphone12 file in the Vim editor.
cat /home/ubuntu/stevejobs/apple/ios/iphone12: Displays the contents of iphone12 using cat.
mv sample/ stevejobs/: Moves the sample directory to stevejobs.
history: Displays the command history.