Linux OS

Linux operating system

• Linux OS (Operating System) is a free and open-source operating system based on the Unix architecture.
• Linux is a multi user multitasking operating system. 
• Linux OS developed by Linus Benedict Torvalds in the year 1991. 
• Linux is a 32 bit and 64 bit operating system. 
• It runs on a wide variety of platforms such as Intel , Sparc ,Alpha etc.
• Linux is distributed as a free software (open source) under a free software License.

Feature of Linux OS:

• Open source

• Secure

• Light weight

• Multi user & multitasking

• Application support for all

Basic components of Linux OS/ Basic Linux elements:

i. Kernel

ii. Shell

iii. File system

Kernel: 

• The kernel is the core part of the Linux operating  system and is loaded into the memory as soon as the system starts up .
• It manages main memory, files peripheral devices, maintaining the time and date, allocating system resources or functions of this part of the OS.
• The kernel is a program at the heart of the linux OS.

Shell: 

Shell is a translator program which interprets(translate) commands given by the user.

File system:

• Linux treats everything as a file .
• All the hardware devices such as mouse ,keyboard ,hard disk also output devices are treated as a file. 
• The linux file is organized in an hierarchy which starts with the root directory . 
• The root is represented by a forward slash (/).
• The file structure of linux are as follows:

/root

 

/root: It is the home directory for root user (admin).

/home: Home directory for root users(user create).

/bin: This directory contains commands used by all users including root user .

/sbin: This directory is used by only root users .

/dev: This directory contains device related files inside.

/etc: This directory contains a system configuration file in the form of a text file .

/lib: This directory contains library files, like a predefined function or method you use that shares its working definition from the library .

/tmp: This directory contains all the temporary files.

/user: This directory contains the home directory of the users. By default software installed in the directory.

/opt: Optional application software packages installed in this directory.(google chrome).

/mnt: This directory contains all the storage devices except the hard disk and mount them as well like CD-ROM, Floppy etc.

/kernel: This directory contains all the kernel specific code.

Linux commands: 

Linux commands are case sensitive . 

You must type all Linux commands in lowercase letters.

File handling in Linux: 

File handling in Linux OS systems is the subject matter of creating and manipulating the file as Linux provides GUI and CUI both the interfaces, here we will learn to work on commands in CUI . In CUI ,we are provided a $ prompt in MS DOS.

Files & directories in Linux OS:

Creating files( cat):

$cat> January press enter

Making new directories(mkdir):

mkdir sales enter

deleting files( rm):

$rm march enter

Moving files(mv):

$ mv rm enter

Removing to a different directory (cd):

$cd sales enter

Removing a directory (rmdir):

$ rmdir exam enter

Listing the contents of directories (ls):

$ ls enter