Linux introduction Class 02

ACE Course CT01558
Linux Introduction
Linux Boot & Installation

 Booting Linux
 Distribution Selection
 Considerations on Installation
 Installation Options
 Basic administration
Linux#2 - Installation 2
Agenda
8/22/2013

System Initialization
BIOS
Boot
loader
Kernel
& device
drivers
init services Login
8/22/2013
Running Linux System

BIOS Initialization
 Power On Self Test recognizes hardware, CPU,
memory, bootable configuration from CMOS
 Bootable devices:
 CD ROM or Floppy
 Drive [IDE, SCSI, SATA, RAID, SSD, SD, microSD, …]
 Network
 USB devices
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The Boot Loader
 Last step in BIOS
 Loads first partition of bootable device
 It can present a menu of OS choices
 Can also let you choose “Other OS”
 Linux boot loaders:
 LILO (Linux Loader) – older, static
 GRUB (GRand Unified Bootloader) dynamic
 Syslinux [for CDs and USBs]
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Kernel Initialization
 Kernel loads based on parameters passed
 All logging goes to /var/log/dmesg
 Detects hardware
 Loads initrd (if necessary)
 Mounts root
 Loads /lib/x.x.x/modules
 Passes control to /sbin/init
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init (Initialization)
 Init loads scripts from /etc/rc.d
 rc.sysinit is the master script at boot time
 Loads networking, drivers, encryption, and provides
[OK] or [FAIL] feedback
 Based on parameter or /etc/inittab default,
it will execute scripts in rc.x (x=runlevel)
 All boot scripts live in init.d,
can be configured via chkconfig
 Last script is rc.local
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UNIX File System
tmp bin usr var etc dev
bin lib
/
local spool
Somewhere
for local
additions
Libraries,
some utilities
and config.
files
Spool files
for batch
utilities
Admin utilities
config. files
Special
device files
Somewhere
everyone
can use
Utilities
System
programs
The top-level “root” directoryPartial view
lib
System
libraries
8/22/2013

 Pre-compiled kernels
 The one downloaded in your distribution
 The one you receive with system updates
 Custom kernels
 The ones you BUILD:
 More security
 Better performance
 Hardware support or Virtualization
8/22/2013Linux#2 - Installation 9
Kernel Features

Kernel Compiler Features

Linux Distributions
Kernel
GNU
X
Other
Linux
Operating
System
Red
Hat
Mint
Ubuntu
Others
+
+
+
+
Installation tools,
configuration tools,
SUPPORT, etc.
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 Mobile Linux
http://en.wikipedia.org/wiki/Embedded_Linux
 Game console Linux http://openpandora.org
 Embedded Linux http://elinux.org
 Automobile consoles & Google TV
 Older hardware
 Printers & Network equipment
Non Distribution Linux

Linux Installation
 PRE
 Hardware Device Configuration
 Software Features
 Deployment Considerations
 Actual Installation
 POST
 Updating, security patches!
 Accounts, groups, services
 Maintenance
8/22/2013

Installing Linux: Hardware
Fedora 13 hardware requirements

Sample pre-installation checklist

 USB media
 DVD media
 FTP server
 HTTP Web server
 NFS server
 SMB server
 Packages on hard disk
16
Installing Linux: Installation Methods
8/22/2013Linux#2 - Installation

Server Design Issues
 Example: Server requirements are very diverse
 Internet or intranet?
 Which services are required?
 Does it require user accounts?
 Heavy or light usage?
 No generic solution
 Each server needs to be carefully designed
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H/W Compatibility & Resources
 Supports a wide variety of CPUs & Architectures
 Linux Hardware ‘How To’ at The Linux Documentation
Project: www.tldp.org
 Know your RAM & Disk requirements
 Server, Desktop, Custom
http://www.tldp.org/HOWTO/Hardware-HOWTO
8/22/2013

Laptops
 Tricky installations
 Custom bus, Video and/or Sound chipsets
 Older laptops may be difficult to install
 Boot from CD, floppy or network
 URL: www.linux-laptop.net
8/22/2013

 USB
 http://www.pendrivelinux.com/
 Virtual Machines
 Virtual Box http://www.virtualbox.com
 Vmware Player http://www.vmware.com
 CLOUD
 Amazon Web Services, Azure, …
USB & Virtual Installs

Block Devices & Filesystem Schemes
 /dev
 Char & Block devices
 Partitions: /dev/hda1… /dev/sda1…
 Filesystem Hierarchy Standard (FHS)
www.pathname.com/fhs
 / /etc /dev /lib/ /bin /boot /sbin
 /usr /home /tmp /var /mnt /proc
8/22/2013

Removable Media
 Mounting means making a foreign filesystem look like
part of the main tree.
 Before accessing, media must be mounted
 Before removing, media must be unmounted
 By default, non-root users may only mount certain
devices (cd, dvd, floppy, usb, etc)
 Mountpoints are usually under /media
can also be defined in /etc/fstab
8/22/2013

Mounting CDs / DVDs
 Automatically mounted in Gnome/KDE
 Otherwise, must be manually mounted
 CD/DVD Reader
 mount /media/cdrom
 CD/DVD Writer
 mount /media/cdrecorder
 eject command unmounts & ejects the disk
8/22/2013

Mounting USB Media
 Detected by the kernel as SCSI devices: /dev/sdaX or
/dev/sdbX or similar
 Type: tail /var/log/messages to find out
 Automatically mounted in Gnome/KDE
 Icon created in Computer window
 Mounted under /media/Device ID
8/22/2013

GUI User Mount Tool
 Run from “Applications”, “System
Tools”, “Disk Management.”
 Allows you to mount or dismount
drives or partitions.
8/22/2013

Disk Partition Layout
M
B
R
Primary Extended Logical
8/22/2013

Partitioning Hard Drives
 GUI or text tools available during install
 Auto or Manual modes
 /boot partition
 Dual boot systems
 Swap partition (2x RAM)
 Create LVM or RAIDs
8/22/2013

Virtual Consoles
 Linux starts with 6 default virtual consoles
 Alt-F1 to Alt-F6 (or CTRL <- ->)
 Can have up to 63 consoles
 Controlled from /etc/inittab
1:2345:respawn:/sbin/mingetty tty1
…
6:2345:respawn:/sbin/mingetty tty6
8/22/2013

System Shutdown and Reboot
 To reboot:
 shutdown –r
 reboot
 init 6
 To halt:
 shutdown –s
 halt
 init 0
 You must be administrator!
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Controlling Services
 service ‘servicename’ function
 Function: start / stop / restart / status
 kill PID
 nice level process
 GUI: “System Tools”,
“System Monitor”
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Monitoring & Process Control
 top – displays top processes
 uptime + ps = w
 ps ax – list of all running processes
 nice PID priority – changes priority level
 Default priority is 10, it can be changed
 from -20 (highest priority) to 19 (lowest)
 kill –signal PID
 killall process
8/22/2013

Hands-on Lab-1
Exploring Linux Services
 From command line type:
 top (press h, q after reading screens)
 w [integrated who / uptime]
 whoami
 ps ax [list all active processes]
 pstree
8/22/2013

Hands-on Lab-2
 su -
 service http start
 service http status
 Or “ps ax | grep httpd”
 killall httpd
8/22/2013

Hands-on Lab-3
 mount
 To view default mounts: ‘more /etc/fstab’
 df –h
 du –sh /var
8/22/2013

 Booting Linux
 Distribution Selection
 Considerations on Installation
 Installation Options
 Basic administration
Summary
8/22/2013

Linux introduction Class 02

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