Presentation By:

Steve Adedayo

A paper delivered during the Energy Information System (EIS) departmental seminar, June 28, 2011 at computer training room, ECN Abuja

Usage share of operating systems for May 2010. Windows XP (50.50%) Windows Vista (21.42%) Windows 7 (14.22%) Mac OS X (5.80%) Linux (1.24%) iOS (iPhone) (0.87%) Other (2.38%)

In order to understand the popularity of Linux, we need to travel back in time, about 30 years ago...Imagine computers as big as houses, even stadiums. While the sizes of those computers posed substantial problems, there was one thing that made this even worse: every computer had a different operating system.

Software was always customized to serve a specific purpose, and software for one given system didn't run on another system.

Computers were expensive, the cost of IT was enormous In 1969, a team of developers in the Bell Labs laboratories started working

on a solution for the software problem, to address these compatibility issues. They developed a new operating system, which was 1. Simple and elegant. 2. Written in the C programming language instead of in assembly code. 3. Able to recycle code.

The Bell Labs’ developers named their project "UNIX.“ Unix was only available in large organizations and was running on Main

frames and mini computers

Linus studying Computer Science at the University of Helsinki sought to have some sort of freely available academic version of UNIX, and promptly started to code.

From the start, it was Linus' goal to have a free system that was completely compliant with the original UNIX.

All features of Unix were added in a few years and many hardware drivers were developed.

Linux is today in use on the desktop, messaging and collaboration, internet, multimedia etc

Modern Linux runs on all major platforms

* Linux is free: * Linux is portable to any hardware platform * Linux was made to keep on running * Linux is secure and versatile * Linux is scalable * The Linux OS and quite some Linux applications have very short

debug-times

Everything that has advantages must have a disadvantage or 2. For Linux, well:

* Too many distributions * ”Hard to Learn” * ”Open Source”

+ Installation + Connecting to the system + Disconnecting from the system + Hardware configuration + Managing Devices + The Linux filesystem + Work effectively on the Unix Command Line + Basic File Management + Process Management + Text and graphic mode + Process Text Streams Using Text-Processing Filters + Software Installation + Advanced Text Manipulation + Using vi + The X environment

In this topic we will cover:. The installation CD – The generic structure of the

CDROM• Local installations • Network installation • Rescue disk – If a Linux system is corrupt, then it is

possible to boot the computer using a rescue disk.• Partitioning• Easy Dual booting

Any Linux distribution has a generic structure of the CDROM containing pre-compiled packages.

Some associated names for the main distributions are:

debian: distmandrake: Mandrakeredhat: RedHatsuse: suse

This is the easiest and most common type of installation and involves the use of the following:

CD-ROM installation – This involves changing the settings in the BIOS for the computer to boot from CD. The installation is menu driven and allows for advanced and basic configuration.

Floppy installation – For this installation you need to create a floppy installation image. This can be an alternative if the CD is not bootable or a non-iso image was downloaded.

For a RedHat installation, this is only a specialized floppy installation. A bootable floppy is made using the bootnet.img image.

The first part of installation is text based and allows for the user to set up network parameters needed. The rest is done via FTP, NFS, or HTTP.

- When an FTP session is opened, data flow is conducted and both ports for sending and receiving are managed by the ftp daemon.

-NFS is a type of remote server. -HTTP is a type of web server.

The rescue disk is a device that makes it possible to boot if the initial Linux system is corrupt. It is basically a small version of Linux that will mount a minimal virtual filesystem into memory.

Linux supports many types of disk devices and formats. Any SCSI or IDE hard disk will work with Linux as with Floppy disks,CD-ROMs,CD-R,Zip and Jaz disks

Most commonly found hard disks on PCs are IDE (Integrated Device Electronics) drives. They feature a relatively simple system interface.

IDE disks offer reasonable performance at a low price point highly desirable for consumer products. A single IDE is capable of attaching 2 disk drives to a system (Master and Slave).

Most PCs have a primary and a secondary IDE interface (4 interfaces can be supported)

On Each disk there may be between 1 and 16 partitions. A partition is a container on the disk where a file system/other partitions can be held

In Linux each partition is assigned an integer number which is appended to the disk drive name.

E.G The first partition on an IDE device /dev/hda is /dev/hda1 There are 3 types of partitions found on a PC:

Primary partitions Extended partitions Logical Partitions

On the other hand SCSI offers excellent performance, lower CPU utilization and a much more flexible connection scheme capable of handling 15 devices on a single bus allowing SCSI systems to grow as space requirements increase without major hardware reconfiguration. Thus this implies higher costs as compared to IDE devices.

Usually IDE is for PCs and SCSI is for servers

This partition must contain a file system. At least one primary partition must exist, and unto four can exist on single physical disk.

They are numbered as: /dev/hda1,/dev/hda2,/dev/hda3,/dev/hda4

At least one of the primary partitions should be marked as active, in which case the PC BIOS will be able to select it for boot.

It is a variant of the primary partition but cannot contain a file system, instead it contains a logical partition.

Only one extended partition may exist on a physical disk and if it exists it takes one of the possible spots for primary partitions leaving room for only 3 partitions.

They exist within the extended partition. 1-12 logical partitions may be created. Logical partitions are numbered 5-16.

A system with one primary partition, an extended partition and four logical partitions are numbered as follows:

/dev/hda1 (Primary)

/dev/hda2 (Extended)

/dev/hda5 (Logical)

/dev/hda6 (Logical)

/dev/hda7 (Logical)

/dev/hda8 (Logical)

Linux has 2 basic options of partitioning disk drives. The fdisk command is a text based program that is easy to use and exists on every Linux distribution.

Fdisk: Manipulate or display the partition table for device using a command driven interactive text interface.

In this topic you will learn: Memory support Resource Allocation – This is done to allow peripherals and

devices on the PC to communicate directly with system resources.

USB Support – Its architecture and classes of devices. SCSI Devices Network Cards Modems and printers

The system’s RAM is always first detected by the BIOS. All types of RAM (EDO, DRAM, and SDRAM) are recognized by the Linux kernel. If problems are encountered with old H/W, that is , when the BIOS cannot detect the RAM, then parameters must be passed to the kernel at boot time.

The primary purpose of resource allocation is to allow peripheral devices and devices on the PC to communicate directly with the system’s resources. These resources are Interrupt Request Lines (IRQ), Input/Output addresses and Direct Memory Access Channels (DMA).

The Universal Serial Bus (USB) is a communication architecture designed to connect to a PC. Used to connect devices like:Display DevicesCommunication devicesAudio DevicesMass Storage DevicesHuman Interface Devices (HID)

Small Computer System Interface (SCSI) is an interface for streaming devices and block storage devices such as tape drives, hard disks, CD-ROMS and other peripheral instruments.

The SCSI defines a bus to which multiple devices are connected. One of the devices in the chain is the SCSI controller, which is the host interface to the other connected SCSI devices.

SCSI types include: SCSI-1, SCSI-2, Wide SCSI, Fast SCSI, Fast Wide SCSI, Ultra SCSI, Ultra Wide SCSI(SCSI-3), Ultra2, Wide Ultra2.

This Network Interface Card (NIC) is used to make the connection between the computer and the network. NICS are configured using hardware jumpers, nonvolatile memory and automated means.

-A modem is device that modulates a digital signal into an analog signal for transmitting information via telephone lines.

-Like NICs and SCSI adapters, modems have a few special considerations during installation.

-Modems also add digital compression and error correction capabilities to increase speed and reliability.

-Most Linux distributions have hardware browser tools (GUIs), which can detect modems, but also setserial can be used to scan the devices.

There are commands which must be run in order to successfully install a printer. The software is built using make, followed by make install.

The printing process in Linux, is Governed by the “Printer capability” file /etc/printcap. This text file defines all of the system’s available print queues and their characteristics.

Use printtool and cupsd

In this topic we cover the following:

Disks and partitionsPartitioning tools – What is needed in which installation

process.Bootloaders – All about LILO the Linux bootloaderQuotas

On a running Linux system, disks are represented by entries in the /dev directory. The kernel communicates with devices using a unique major/minor pair combination. All major numbers are listed in /proc/devices. For example the first IDE controller‘s major number is 3:

Block devices (1 ramdisk, 2 fd, 3 ide0)Hard disk descriptors in /dev begin with hd (IDE) or sd

(SCSI), a SCSI tape would be st, and so on. Since a system can have more than one block device, an additional letter is added to the descriptor to indicate which device is considered.

Disks can further be partitioned. To keep track of the partitions a number is added at the end of each physical device.

Table 2 Partitions hda1 First partition on first hard disk

hda2 Second partition on first hard disk

sdc3 Third partition on third SCSI disk

IDE type disks allow 4 primary partitions, one of which can be extended. The extended partition can further be divided into logical partitions. There can be a maximum of 64 partitions on an IDE disk and 16 on a SCSI disk.

These tools are grouped into:a) Before installation tools – This involves the use of

PartitionMagic or FIPS. PartitioningMagic is much more versatile and can handle most common UNIX formats as well.

b) During installation – In this stage, the Linux partition is partitioned again.

While installing Linux you will have the choice of creating new partitions and associating each partition to a mount point.

For advanced users this is done in two steps:Use the fdisk tool to create new partitionsAssociate a mount point to each partition

For intermediate users most distributions include a user friendly tool that does both these steps at once:diskdrake (Mandrake) DiskDruid (RedHat)Cfdisk (Debian)

Upon power on, the CPU begins processing instructions from the Read Only Memory usually the basic input output system (BIOS)

Instructions in BIOS perform basic initialization chores to discover and configure peripheral hardware and begins looking in known locations for the operating system (or the operating system loader). When the OS is launched it begins an initialization sequence of its own.

The MBR occupies the first sector of the disk (512 bytes) and contains the partition tables together with a bootloader. At boot time the bootloader reads the partition tables looking for a partition marked “active” and loads the first sector of this partion.

2 Boot loaders in Linux ( LILO & Grub)

There are roughly 3 parts involved:1. LILO: This is the loader itself. LILO is installed on the

MBR and loads the second stage bootloader, generally situated in /boot/boot.b.

2. /etc/lilo.conf3. /sbin/lilo: This binary reads it’s configuration file

/etc/lilo.conf and installs the LILO bootloader./sbin/lilo should be run every time a change is made to /etc/lilo.conf

boot* where LILO should be installed (/dev/hda is the MBR) install which second stage to install (boot.b is the default) prompt give the user a chance to choose an OS to boot default name of the image that will be booted by default timeout used with prompt, causes LILO to pause (units are 1/10 of a sec) image* path to the kernel to boot (one can use ‘other’ to chain load) label* name of the image. This is the name a user can type at the boot prompt root* the name of the disk device which contains the root filesystem / read-only* mount the root filesystem read-only for fsck to work properly append give kernel parameters for modules that are statically compiled. linear/lba32 these options are mutually exclusive. Both ask LILO to read the disk

using Linear Block Addressing. linear is typically used for very large disks. Lba32 is used to

allow boot time access to data beyond the first 1024 cylinders.

GRUB – Grand Unified Bootloader GRUB is also installed on the MBR. You can either alter this MBR

with the /sbin/grub shell or use a configuration file called /boot/grub/grub.conf which will be read by /sbin/grub-install

THANK YOU