CIS 191 – Lesson 2

SystemAdministration

CIS 191 – Lesson 2

System Architecture

• Component Architecture– The OS provides the simple components

from which you build complex applications.

• Client/Server Architecture– Applications are separated, usually across a

network, into one component that listens for requests and provides a resource to a second component – the client

• Layered Architecture– Complex programs are created with layers

of software each having well defined interfaces.

CIS 191 – Lesson 2

software

Layers of a multi-user multi-tasking operating system

users

hardware

operating system

applicationssystem commands

libraries

kernelsystem call interface

resource management

device drivers

CIS 191 – Lesson 2

Operating System

Juggles users & programs across limited hardware resources• Runs programs for multiple users• Provides common services for programs and users• Shares hardware resources between competing programs and users

users

programs

hardware

Basic role of a multi-user multi-tasking operating system

CIS 191 – Lesson 2

Architecture DependentKernel Code

KernelSpace

ProcessManagement

MemoryManagement

Network Stack

Virtual File System

UserSpace

Device Drivers

Kernel1

Hardware

System Call Interface

Users

Commands & Utilities

Shell

X / Desktops

(multi-user)

GNU C Library (glibc)

Programs (multi-tasking)

Applications

1See “Anatomy of the Linux kernel” by M. Tim Jones at http://www-128.ibm.com/developerworks/linux/library/l-linux-kernel/

GNU/Linux Operating System Architecture

Richard Stallman started the GNU project in 1983 to create a free UNIX-like OS. He Founded the Free Software Foundation in 1985. In 1989 he wrote the first version of the GNU General Public License

Linus Torvalds, as a student, initially conceived and assembled the Linux kernel in 1991. The kernel was later re-licensed under the GNU General Public License in 1992.

CIS 191 – Lesson 2

rootlypowers

CIS 191 – Lesson 2

Root Account and Superuser

• “Superuser” privileges include installing software and modifying system configuration files.

• The administrator account is named root.

• root has all superuser privileges and is “all-powerfull”. Be very careful when logged on as root!

• Ways to obtain root privilege:• login as root (need to know root password)• login as regular user and use the su command

(need to know root password)• login as regular user and use the sudo

command. (do not need to know root password, but need to preconfigure /etc/sudoers file.

CIS 191 – Lesson 2CIS 191 – Lesson 2

Root Account and Superuser/etc/passwd

Root account

uid=0 gid=0 Home directory

CIS 191 – Lesson 2CIS 191 – Lesson 2

For each top level directory, determine the following:

1. How many files are contained therein? find . | wc –l

2. How much disk space is being used?du –sh .

3. What is the predominant type of file in the directory?file * | more

4. cd ../next

The High Hurdles Exercise

CIS 191 – Lesson 2

Essential Tasks

• Software Installations and Upgrades• Maintaining Hardware• Performing Backups• Managing User Accounts• Monitoring the System• Troubleshooting• Helping Users• Maintaining Local Documentation

CIS 191 – Lesson 2

Types of Installations

• CD, DVD, or ISO image• Live CD/DVD• Attended vs. Unattended• Local vs. Network• Imaging software (Ghost, ImageCast)• Build from scratch

CIS 191 – Lesson 2

Three steps to an installation

1. Prepare the storage devicePartition the disk

Format the filesystems Select mount points for those filesystems

2. Copy the selected packagesPackage groups, packages, files

3. Write out the boot loaderMBR or boot sector (GRUB, LILO, SYSLinux)

Everything else is configuration