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Summery Linux All

- redhat is a kernel for centos
1/- What is linux ?
  is a os aplication

- linux is kernel for open soft. have kernel + Shell
  shell is user interface have too : CLI (comment line interface=Bash)+ GUI ( grapfic user interface= KDE)
- redhet and centos
Application have:
- System utility : /bin( Store user command ) & sbin ( System command )
- service : Email , Website ..

Kernel : Core OS : control hardware and support driver and manage all hardware operation. 
kernel + shell + application = complete OS
===========================================
- in 1984  = build Unix
- 1991      = build Linux is a kernel unix

under kernel Unix have : linux, MAC, Solaris

2/ Linux Distribution : ( version of Linux = OS + collection of software )
Asterisk@home : use for do VOIP
have :
1. Redhat : CentOS (use for server), Fedora...
2. Debian : Ubuntus( for desktop and server )
3. OpenSUSE : SUSUE ENterprise
=> GUL = Free Listence  => GNU

now 80% use Centos because : 
  - Free software
  - Free Support
  - Stable

3/. Linux Features: 
 - Support all hardware
 - Security
 - Muti user
 - Shell ( input user ) have command line and desktop 
 - Open source  ( can edit OS build new OS and free listence )
- Muti programing ( can open alot program )

4/. Linux Boot Process : 
when power on / restart hardware is  :
- System stratup /hardware installation :  BIOS /System start : 
- Boot loader stage 1 : MBR loading ( in window c: file bootmgr is boot manager )
    have 2: 
      - MBR :  Master boot record : 1st Sector : 0 of HDD( when format HDD partition is build MBR in drive )
      - VBR :  Volume boot loader : patition boot loader
                     => Sector : 1 ( sector is blog in HDD) sector 0 store boot loader OS.
                                   - window boot namager : load/boot OS in memery
                                   - linux : GRUB use for boot linux
                     => Sector : 2 ( store DATA window  OS )
- Boot loader stage 2 : GRUB Boot loader
- Kernel : Linux OS
         OS mode :
                        - Safe mode : troubleshoot & fix error windows
                        - Normal mode : destop : full function : user
         OS mode : linux : Run Level mode
                    - 0 = shudown mode => #init 0
                    - 1,2 = Safe mode => #init 1,2
                    - 3 = CLI mode => #init 3
                    - 5 = GUI mode => #init 5
                    - 6 = Reboot => #init 6
- INIT process : Run levels
- User prompt : User commands

5./ Prepare Dell Server for Linux Installtion
  1. check system requirement for Centos 7
  2. Download Centos 7 ISO file
  3. Burn it with Flash or DVD (can use software : rufus 2.5.exe)
  4. Start booting to Flash or DVD for installation begin
  OS version : 6,7
  Processor CPU : 226Hz for version 6
  RAM : minimum ( V6: 768 MB V7: 1GB ) recommended V6: 1GB, V7 :2 GB )
  Disk space : minimum V6: 20GB, recommended V6 : 40GB)
   configure RAID : 
     - RAID 1 = OS (/, /boot, swap) ( HDD 2 up )
               / is root : all sub directories ( for window /=c: )
               / boot : GRUB ( boot OS )
               / Swap : page file = virtual memory for build virual RAM  
               
     - RAID 5,6,10 = Data (/home, .data) (3,4,4 HDD)
              / home : store user data
              / data : backup document

7/. Linux Directory Structure
/ :is root directory for the entire file system ( for window = drive C: is a main deratories)
bin/ :Essentail user command : is a user command( system linux) ( sub deratories )
boot/ : boot loader's files : is boot loader ( system linux ) ( sub deratories )
dev/ : device files : is hardware devices all ( sub deratories )
etc/ : System configuration files :  is store comfiguration have mail, web... (conmand cd /etc) (sub deratories)
home/ : User home directories : is store user directories ( sub deratories )
lib/ : Essential shared libraries and kernel module : is library store kernel module and essential  ( sub deratories )
root/ : Super user's home directory : is a home deratories user root( sub deratories )
proc/ : virtual files/process status text files : is a process virtual files and status text file ( sub deratories )
media/ : mount point for removable media : is use for munt removable flsh or DVD (sub deratories)
mnt/ : Mount point for the temoirary file systems is a mount point folder ( sub deratories )
opt/ : other application : is objuct ( sub deratories )
sbin/ : system binaries : is a system command EX: shutdown or reboot ,( sub deratories )
srv/ : data for services : is store data for services ( sub deratories )
tmp/ : Temporary filles : is store file run ( sub deratories )
usr/ : multiuser utilities and applications : is a file OS for windows is file folder windows in drive C ( sub deratories )
var/ : variable files : is store error log ( sub deratories )

8/. linux Files Structure : 




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