CIT 140: Introduction to IT Slide #1

CSC 140: Introduction to IT

Operating Systems

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Questions

• What is an operating system?

• What services does it provide?

• What’s the difference between CLI and GUI?

• What types of OSes are out there?

• How can I use UNIX?

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What is an Operating System?• Program to help you use the hardware:

– CPU– Memory– Disk– Other I/O: graphics, sound, printers, etc.

• Properties provided by an Operating System– Ease of use.– Efficiency.– Fairness.– Reliability.– Security.

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Layered View of a Computer System

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Two Views of an OS

1. Top-down– E.g., The OS performs the task of dealing with

complicated hardware resources and gives you a comprehensive and simple machine, ready to use.

– In this way, the OS provides a virtual machine.

2. Bottom up– E.g., the OS decides how much space how much

RAM space is to be allocated to a program before it is loaded and executed.

– In this way, the OS is viewed as a resource manager.

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Operating System Services

• Execution of a program• Input and output operations performed by

programs• Communication between processes• Error detection and reporting• Manipulation of all types of files• Management of users and security

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CLI vs GUI

• CLI– Input device is a keyboard.– Communicate by typing in a computer language.

• Graphical User Interface– Input is taken from a point-and-click device.– Communicate by filling out forms.

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Types of Operating Systems

• Single-user, single-process system– MS-DOS, MacOS 9, MS Windows 3.1.

• Single-user, multiprocess system.– MS Windows 95, 98, ME.

• Multiuser, multiprocess system– MS Windows NT, XP.– UNIX.– VMS.– Mac OS X.

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Structure of a UNIX command#command [[ - ] option(s)] [option argument(s)] [command argument(s)]

Examples:

• $ ls• $ ls -la• $ ls -la m*• $ lpr -Pspr -n 3 proposal.ps

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Logging On and Logging Off

• General Categories– Local Area Network (LAN) Connection.– Internet Connection.– Stand-Alone Connection.

• For the first lab, we will be logging ontozappa.nku.edu

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1. Connecting via a UNIX Terminal

login: your_username <Enter>password: your_password <Enter>Last login: Sun Aug 28 19:35:32 2005 from foo.com.You have new mail.Terminal type? [vt100] <Enter>Sun Microsystems Inc. SunOS 5.9 Generic May 2002

NOTICE: April 19, 2005 – The upgrade to Java JDK1.5.2 has been completed.

#

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2. Connecting via PuTTY on a Microsoft Windows Machine

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3. Connecting via a Telnet Client on a Microsoft Windows Machine.

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File Maintenance Commands

• What is File Maintenance?

• File and Directory Structure– Home Directory– Current Working Directory

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File Maintenance Commands

Viewing the Contents of Files– cat, more, less

# cat > myfile

This is an example of how to use the cat command to add plain text to a file

<Ctrl-D>

# more myfile

This is an example of how to use the cat command to add plain text to a file

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File Maintenance Commands

Creating, Deleting and Managing Files– cp, mv, rm, ls# cp myfile myfile2# mv myfile2 renamed_file# mv “latest revisions october.txt” laterevs.txt

# rm renamed_file# lsDesktopMailmyfile myfile2# ls –al

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File Maintenance Commands

Creating, Deleting and Managing Directories–mkdir, cd, pwd, rmdir# mkdir first

# cd first

# pwd

/home7/smithj/first

# cd

# pwd

/home7/smithj

# cp myfile myfile2

# ls my*

myfile myfile2

# rmdir first

rmdir: first: Directory not empty

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Obtaining Help with man

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Obtaining Help with man

man [options][-s section] command-list

# man lsUser Commands ls(1)

NAME

ls - list contents of directory

SYNOPSIS

/usr/bin/ls [-aAbcCdfFghilLmnopqrRstux1@] [file...]

/usr/xpg4/bin/ls [-aAbcCdfFghilLmnopqrRstux1@] [file...]

DESCRIPTION

For each file that is a directory, ls lists the contents of

the directory. For each file that is an ordinary file, ls

repeats its name and any other information requested. The

output is sorted alphabetically by default. When no argument

is given, the current directory is listed. …

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• whatis# whatis login setenvlogin login (1) - sign on to the systemsetenv set (1) - shell built-in functions to

determine the characteristics for environmental variables of the current shell and its descendents

• apropos# apropos webneon neon (3) - HTTP and WebDAV client libinstaller installer (1m) - Solaris Web Start installersmcwebserver smcwebserver (1m) - start the Sun consolewbem wbem (5) - Web-Based Enterprise Mgmt

Other Forms of Help

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Utility Commands• Examining System Setups

– whereis, whoami, uname# whoamismithj# whereis mkdirmkdir: /usr/bin/mkdir

# uname -a

SunOS zappa 5.9 Generic_112233-07 sun4u sparc SUNW,Ultra-250

• Communication Commands– write username

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Command Aliases • The alias command creates new names for commands.

• Syntax for the alias command is:

alias name=string

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Logging Off

• Exit# exit

Logout

Connection to zappa.nku.edu closed.

• Ctrl-d will do the same thing.