# What is Linux ?

### What is Linux?

Linux is an open-source software operating system, which was developed by Linus Torvalds in September 1991.

Today many year pass and Linux become one of the most popular operating systems.

Today 90% of the fastest supercomputers out of 500 runs on Linux.

When we open Linux os and see a black screen that is nothing but a shell. Shell wrote in c/c++ language. shell communicates with the kernel via commands. Krenel directly communicates with the hardware.

**Following is Linux Directory Structure:-**

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1681365532957/a022d810-61a9-478e-a02c-b48297c8370c.png align="center")

**The following are commands of Linux:-**

*pwd*:- It shows the present working directory.

*ls*:- It shows the available files.

*uname*:- It shows the username.

*uname -r*:- It shows a version of the kernel.

*cd***:**\- It is used for changing the directory.

*clear*:- It is used to clear the screen.

*whoami***:**\- It shows the current login user name.

*history*:- It shows a list of previously used commands.

*date*:- It shows the time and date.

**Commands for directory and files:-**

*mkdir:-* It is used to create the directory.  
Syntax*:- mkdir FolderName*

*touch*:- Create the file.  
Syntax:- *touch FileName*

*rm -r*:- Remove everything from the directory.  
Syntax:- *rm -r FolderName*

*useradd*:- Add the user.  
Syntax:- *useradd UserName*

*passwd*:- Changing or setting the password of the user.  
Syntax:- *passwd UserName*

*su*:- Switch the user.  
Syntax:- *su UserName*

*echo*:- print anything in the file.  
Syntax:- *echo "anything writes you want...."*

*mv*:- Rename  
Syntax:- *mv old\_file new\_File*