What is LINUX?
LINUX is a flavour of UNIX.
* Unix is an operating system which acts as link b/w user and computer.
* Unix is a multiuser system. Several people can use a UNIX computer at the sametime.

Parts of unix:
Kernel- Heart (interacts with the hardware)
Shell – Utility that processes your request. works like interpreter. used to control the kernel.
Tools -Offer addition functionality to the OS.

OS
It is a software used to manage the resources in the computer and provides an interface to access the resources.
EX: windows,mac,linux etc.

Functions of OS:
1.process management
2.Main-memory Management-RAM
3.Secondary -storage management-ROM
4.I/o System management
5.File management
6.Protection System
7.Networking
8.Command-Interpreter System

File System:
Logical method of storing and organizing large amounts of information in a way it is easy to manage.

/ : root of file system
/bin : binaries
/boot: files for successful booting are present
/dev: stands for devices.
/etc: System wide configuration files.

FILE PERMISSIONS:
x execute-1
r read-4
w write-2
+ add permision
– remove permission
u user
g group
a all

Commands:
chmod u+x filename
— file is provided with execute permission

with numbers:
chmod 644 filename
–6 means 4+2 i.e read and write
–0 is no permision
— in 644, 6 is for user,4 is for group and other 4 is for others.

To see the file permission
ls -l filename