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Tutorial on Linux Introduction, Installation & Initial Setups. Speaker: Faran Javed (BIT-5) Abdul Lateef Khan (BIT-5). Agenda. Introduction Planning to Install Installing Red Hat Linux Post Installation Configuration First Steps with Linux. Part – I Getting Started. Introduction.

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tutorial on linux introduction installation initial setups

Tutorial on Linux Introduction, Installation & Initial Setups

Speaker:

Faran Javed (BIT-5)

Abdul Lateef Khan (BIT-5)

agenda
Agenda
  • Introduction
  • Planning to Install
  • Installing Red Hat Linux
  • Post Installation Configuration
  • First Steps with Linux
introduction
Introduction
  • For x86 architecture
  • Free implementation of UNIX
  • Used for
    • Programming
    • Productivity
    • Distributed Computing
    • Telecom & Networking
slide6
The core kernel of a free operating system first developed and released to the world by Linus Bendict Torvalds in 1991
slide8
Product of Red Hat Inc.
  • Named after a Cornell university team hat.
  • Objective:
    • Develop release and market an easily managed, and easy to use Linux Distribution
brief history
Brief History
  • Initiated by Linux Torvalds
  • Initially the little Clone of Unix
  • Version 0.0.1 was never announced
  • Version 0.0.2 announced October 5 1991
  • Aim was to build a MINIX look-a-like OS for AT 386 machines
system features
System Features
  • complete multitasking, multi-user operating system
  • Complete Implementation of the TCP/IP stack and other networking software is provided
  • Variety of File systems supported
    • Ext2
    • Ext3
    • XENIX and UNIX System V
    • Microsoft MS-DOS
    • Windows 95 VFAT file systems on a hard drive or floppy.
    • The ISO 9660 CD-ROM file system is also supported.
system features1
System Features
  • The kernel supports demand-paged, loaded executables.
    • Only those segments of a program which are actually in use are read into memory from disk.
  • unified memory pool for user programs and disk cache.
    • All free memory is used by the cache, which is reduced when running large programs.
  • Executables use dynamically linked, shared libraries
system features2
System Features
  • To facilitate debugging, the kernel generates core dumps for post-mortem analysis.
  • amount of available memory, Linux also implements disk paging
  • If several instances of a program are running at once, they share physical memory, which reduces overall usage.
software features
Software Features
  • Coming Up in Later Slides
linux installation
Linux Installation
  • Hardware Compatibility
    • http://hardware.redhat.com/hcl/
  • Disk Space
    • 400 MB – 5 GB depending on minimal, personal, server etc. settings
preparing for the install process
Preparing for the Install Process
  • Most Common Installation Methods
    • CD-ROM
    • NFS
      • From a remotely mounted hard drive containing the red hat Linux software
    • FTP
    • HTTP
    • Hard Drive Partition
preparing to install from a cd rom
Preparing to Install from a CD-ROM
  • Just make sure System BIOS is set to BOOT from CD_ROM
partitioning your hard disk space
Partitioning Your Hard Disk Space
  • If Linux is the only OS than we can auto partition
  • Assuming a machine with 20 GB Hard Disk & 256 MB RAM
  • Most basic Scheme Requires a native root partition & a swap partition
typical partitions
Typical Partitions
  • For a machine with only Linux on the system the scheme will look like:
    • Hard Drive Partition Mount Point Size

/dev/hda1 / 19.14 GB

/dev/hda2 swap 512 MB

  • For a machine already having windows:
    • Hard Drive Partition Mount Point Size

/dev/hda1 /mnt/dos 9.74 GB

/dev/hda2 / 8.14 GB

/dev/hda3 swap 512 MB

hosting parts of the linux file system on partitions
Hosting Parts of the Linux File System on Partitions
  • /home
    • Our users home – will contain our personal files,
  • /opt
    • Directory for additional software packages to be installed
  • /tmp
    • Used as temporary storage for users
  • /usr
    • Holds nearly all software on the red hat system
  • /var
    • Security logs, mails, print spools are under this directory
kickstart installation method
Kickstart Installation Method
  • Automation always saves time
  • Use Red Hats KickStart Configurator
  • A sample ks.cfg file

#System Language

Lang en-US

#Langugae Modules to Install

Langsupport en_US

sample file
Sample File

# System Keyboard

keyboard us

# System mouse

Mouse genericps/2

# System time zone

Timezone –utc America/NewYork

# Root password

Rootpw – iscrypted $1$shaldsgfakd3452435gjAJHSGDA/SAD324

the installation process
The Installation Process
  • Language Selection
  • Keyboard and Mouse configuration
  • Choice of installation type
    • Personal Desktop
      • If new to the world of Linux
    • Workstation
      • If you would like a graphical desktop environment, as well as software development tools
    • Server
      • If you would like your system to function as a Linux-based server
    • Custom
      • Greatest flexibility
    • Upgrade
installation process cont
Installation Process (cont.)
  • Disk partitioning
    • Automatic Partitioning
    • Manual Partitioning
      • ext2, ext3, RAID, swap, vfat etc.
  • Configuring Boot Loader
    • LILO
    • GRUB
  • Network Configuration
  • Firewall Configuration
  • Language & Time Zone Configuration
installation process cont1
Installation Process (cont.)
  • Authentication setup
  • Package Selection
  • Actual installation
  • Boot Disk creation, VGA and monitor configuration
basic linux directories
Basic Linux Directories
  • / The root Directory
  • /bin Essential Commands
  • /boot Boot Loader Files
  • /dev Device Files
  • /etc System Configuration files
  • /home User home directories
  • /lib Shared libraries
  • /mnt usual mount point
  • /opt Add-on software packages
  • Proc Kernel Information Process control
  • /root Super user
  • /sbin System commands mostly root only
  • /tftpboot Network boot support
  • /tmp temp files
  • /Usr Secondary software file hierarchy
  • /var Variable data (e.g. logos), spooled files
files in the etc directory
Files in the /etc directory
  • Fstab
    • FILE SYSTEM TABLE. A text file listing each hard drive, Floppy drive or other storage attached to your PC.
  • Inittab
    • The system Initialization table. Defines default run level. Here we can define either to use text or GUI mode.
  • Modules.conf
    • Contains directions and options used when loading kernel modules to enable various types of hardware
  • Passwd
    • The list of users of the system & their accnt info.
  • Printcap
    • Systems printer capabilities database
  • Shells
    • A list of approved shells (command line interfaces)
  • Sysconfig
    • Tree –afx /etc/sysconfig
interact with the kernel
Interact with the kernel
  • Use the proc diractory
  • Vi /proc/meminfo
  • Or use the free command
  • /proc/cpu -- cpu family,type & speed
  • /proc/net – important networking info
    • /proc/net/netstat , /proc/net/route , /proc/net/dev
  • /proc/version – kernel version
remote login
Remote Login
  • Use SSH – secure shell
  • Linux also supports :
    • Telnet
    • Rlogin
changing user information
Changing user Information
  • Chfn – change finger information
  • Finger – get finger information
accessing documentation
Accessing Documentation
  • Apropos partition
  • Will display related commands
using the man pages
Using the Man pages
  • Man rm
  • Will display manual pages for the rm command
slide35
Grep
  • Grep alateef /etc/passwd
  • This will search for alateef in /etc/passwd
  • Whereis fdisk
using environment variables
Using Environment Variables
  • PWD – current directory
  • USER – declare user name
  • LANG – To set language defaults
  • SHELL – TO declare the name and location of the current shell
  • PATH – set default location of executable files
  • LD_LIBRARY_PATH – location of important software libraries
  • TERM – set the type of terminal in use
  • MACHINE – declare system type, architecture & so on
  • $env
  • /etc/profile
navigating searching with shell
Navigating & searching with shell
  • Cd /home/…..
  • Cd ..
  • Whereis
  • Locate
  • Apropos
  • Cat – contents of file
  • Less - allows scrolling while reading contents of file name
  • Mv
  • Mv
  • Cp
  • Rm
  • Rmdir
  • Grep
compressing decompressing files
Compressing & Decompressing Files
  • Bunzip2 - expands a compressed file
  • Bzip2 – compresses or expands files & directories
  • Gunzip
  • Gzip
  • Shar
  • Tar
  • unshar
using text editors
Using Text Editors
  • Ed
  • Emacs
  • Jed
  • Joe
  • Mcedit
  • Pico
  • Sed
  • Vim
  • Vi
  • Gedit
  • Kate
  • Kedit
  • Nedit
  • kwrite
working with vi
Working with vi
  • H,j,k,l – cursor movement
  • Delete character – x
  • Delete line – dd
  • Mode toggle – ESC, Insert (or i)
  • Quit - :q
  • Quit without saving - :q!
  • Save file - :w
  • Text search - /
  • Run a shell command - :sh (use exit to return)
ethernet configuration
Ethernet Configuration
  • Things you should know
    • IP address
      • If you're configuring loopback mode, it is 127.0.0.1
    • Subnet mask
      • It is always 255.0.0.0 for loopback address
    • Broadcast address
      • It is equal to your subnet address with 255 replaced as the host address
    • IP address of Gateway
    • IP address of Name server
configuration using system scripts
Configuration using system scripts
  • Edit the file /etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE=eth0

ONBOOT=yes

BOOTPROTO=static

IPADDR=192.168.8.139

NETMASK=255.255.255.0

BROADCAST=192.168.8.255

GATEWAY=192.168.8.1

  • Edit the file /etc/sysconfig/network

NETWORKING=yes

HOSTNAME=linux.niit.edu.pk

GATEWAY=192.168.8.1

configuration of static ip via command line
Configuration of Static IP via command line
  • The shell provides two programs for NIC configuration, ifconfig & route
    • ifconfig
      • For configuring the network device interface with certain parameters, such as the IP address, subnetwork mask etc.
      • Remember to bring the interface down & up when modifying
      • Set IP Address

ifconfig lo 127.0.0.1

ifconfig eth0 192.168.75.20 netmask 255.255.255.0

      • Verify Settings

ifconfig eth0

    • route
      • To show and manipulate the IP routing table
      • Add default gateway

route add default gw 192.168.1.254

route add –net 192.156.79.0 netmask 255.255.255.0 dev eth0

important configuration files
Important Configuration files
  • /etc/hosts
    • Contains a list of IP addresses and the hostnames they correspond to

127.0.0.1 ENT localhost.localdomain localhost

  • /etc/networks
    • lists the names and addresses of your own and other networks
    • Used by the route command and allows you to specify a network by name instead of by address

default 0.0.0.0 # default route - mandatory

loopnet 127.0.0.0 # loopback network - mandatory

niit-net 202.83.166.171 # Modify for your own network address

important configuration files1
Important Configuration files
  • /etc/host.conf
    • Specifies how your system resolves hostnames

order hosts,bind

  • /etc/resolv.conf
    • Configures the name resolver
      • specifies the address of your nameserver (if any)
      • domains that you want to search by default if a specified hostname is not a fully specified hostname

domain niit.edu.pk

nameserver 10.10.10.1

network configuration for dhcp
Network Configuration for DHCP
  • Edit the file /etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE=eth0

ONBOOT=yes

BOOTPROTO=dhcp

IPADDR=

NETMASK=

BROADCAST=

GATEWAY=

  • Edit the file /etc/sysconfig/network

NETWORKING=yes

HOSTNAME=

GATEWAY=

basic ppp configuration for modems
Basic PPP Configuration for Modems
  • In Windows, modems and other serial devices are named COM1, COM2 etc.
  • In Linux, these are referred as /dev/ttyS0, /dev/ttyS1
    • At installation time a symbolic link called /dev/modem will be created for the modem
  • KDE graphical tool called “kppp” configures a dialup connection easily
  • Located in /usr/bin/kppp
  • Red Hat requires the root password to be entered each time kppp is executed for security reasons
  • Some distributions allow any user to execute this program such as SuSE
configuring kppp
Configuring kppp
  • Start kppp
  • Click the Setup button and then click the Device Tab
slide54
You might need to add the line route add default ppp0 to the field Execute program upon connect: to ensure the default gateway is set to the default gateway from your ISP.
user accounts
User Accounts
  • Personal Accounts
    • AAA (Authentication, Authorization, Accounting)
  • Administrative Accounts
    • root
    • Accessed using the su command
  • Daemon accounts
    • e.g., news daemon
the passwd file
The passwd File
  • Every account on the system has an entry in the file /etc/passwd

username:password:uid:gid:gecos:homedir:shell

  • Username
    • A unique character string, identifying the account
  • Password
    • An encrypted representation of the user's password
  • UID
    • unique integer the system uses to identify the account
  • GID
    • an integer referring to the user's default group, found in the file /etc/group
  • gecos
    • Misc. information like user's real name, office address or phone no. etc.
the passwd file1
The passwd File
  • homedir
    • user's home directory
  • shell
    • name of the program to run when the user logs in e.g., /bin/bash or /bin/tcsh

root:ZxPsI9ZjiVd9Y:0:0:The root of all evil:/root:/bin/bash

shadow passwords
Shadow Passwords
  • Encrypted passwords in /etc/passwd are potential security risk
  • Instead /etc/shadow is used
    • Contains the real encrypted passwords
    • Readable only by root
    • Contain similar fields but empty or bogus values
  • passwd command
    • -n : sets the minimum number of days between changes
    • -x : the maximum number of days between changes
    • -w : the number of days a warning is issued before a password expires
    • -i the number of days of inactivity between the expiry of a password and the time the account is locked
the group file
The Group File
  • To logically organize sets of user accounts
  • To allow users to share files within their group or groups
  • Every user is assigned to at least one group
  • The file /etc/group contains a one-line entry for each group on the system

groupname:password:gid:members

  • password is an optional encrypted password associated with the group, which allows users not in this group to access the group with the newgrp command
  • members is a comma-separated list of usernames identifying those users who are members of this group but who have a different gid in /etc/passwd

root:*:0:

bin:*:1:root,daemon

users:*:50:

bozo:*:51:linus,mdw

megabozo:*:52:kibo

creating accounts
Creating Accounts
  • Adding an entry to /etc/passwd
  • Creating the user's home directory
  • Setting up the user's default configuration files
  • adduser or useradd
deleting and disabling accounts
Deleting and Disabling Accounts
  • To delete an account
    • remove the user's entry in /etc/passwd
    • remove any references to the user in /etc/group
    • delete the user's home directory
    • any additional files created or owned by the user

userdel -r lateef

  • Disabling a user account
    • add an asterisk to the first character of the password field of the /etc/passwd entry

kashif:*BjDf5hBysDsii:104:50:lateef Rao:/home/aclark:/bin/bash

modifying user accounts
Modifying User Accounts
  • Simply edit /etc/passwd and /etc/group
  • To change a user's password, use the passwd command
  • Use chown command to change ownership of files

chown -R alateef /home/alateef

file ownership and permissions
File Ownership and Permissions
  • Permissions refer to the ways in which someone can use a file or directory
    • For files
      • Read permission means you can look at the file's contents
      • Write permission means you can change or delete the file
      • Execute permission means you can run the file as a program
slide66
File Ownership and Permissions
    • For directories
      • Read permission means you can list the contents of that directory
      • Write permission means you can add or remove files in that directory
      • Execute permission means you can list information about the files in that directory
  • Who gets these permissions?
    • Linux has three levels of permissions
      • Owner
      • Group
      • Other
owners and groups
Owners and Groups
  • Each file has an owner and a group
changing the owner group
Changing the Owner, Group
  • Common mistake when creating a directory under /home for a new user as root
  • chowncommand changes the owner of a file
    • only root can use chown for changing ownership of a file
  • chgrpcommand changes the group
    • any user can change the group to another group to which he belongs

# chown root /home/lateef/apache.conf

# chgrp bin /home/lateef/apache.conf

# chown root.bin /home/lateef/apache.conf

changing the permissions
Changing the Permissions
  • The permissions are also called the file's "mode"
  • The command that changes permissions is chmod
  • Symbolic Mode

$ chmod +x header.c

$ chmod u-x header.c

$ chmod ug+rwx header.c

  • User permission is u, group permission is g, and other is o
changing the permissions1
Changing the Permissions
  • Absolute Mode
    • in terms of bits and octal notation

$ chmod 400 header.c

$ chmod 555 header.c

  • To set the default mode that is assigned to each file you create
    • umask command

$ umask 027

shutting down the machine
Shutting down the machine
  • Shutdown –h now
  • Or shutdown –h 0
  • Shutdown –h 18:30 “system is going down for maintenance”
  • Shutdown –r now
  • shutdown –r 0
references
References
  • http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/install-guide/
  • Red Hat Linux 9 Unleashed – Bill Ball & Hoyt Duff
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