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Computer Systems
2009-2010
Week 11: The Command Line
Interface
Alma Whitfield
What we have done so far



Files organised into directories
Directories form a hierarchy
Manipulated files using Windows

Windows Explorer
2
What we are going to do today


Examine the MS-DOS operating
system’s command line interface
Look at how MS Windows has
developed from MS-DOS
3
Organising files


Thousands of files can be held in
secondary storage
Organising the files is a job for the
operating system
4
Operating systems

An operating system is software installed
on the computer to make it possible to
use it without needing a degree in
electronic engineering
5
Operating systems: mini-history

Early machines had no operating system
– you needed to be an engineer to run a
program


Could only run one program at a time
The CPU spent most of its time waiting for
hardware to complete tasks like printing or
writing to or reading from disc
6
Operating systems: mini-history

By the 1960s, operating systems could
run several programs at the same time

While one program is waiting for a read from
disc, another could be executing
7
Operating systems: early 1980s

Microsoft introduced PC operating
system called MS-DOS



Microsoft Disc Operating System
Disc operating system means file
organisation
Instructions typed in at a command line
8
Operating systems: early 1980s

Microsoft introduced PC operating
system called MS-DOS



Microsoft Disc Operating System
Disc operating system means file
organisation
Instructions typed in at a command line
9
MS-DOS uses a
Command Line Interface


Do not use mouse
Type in commands as words


Use a Command Prompt box


i.e. lines of command
Start | Programs | Accessories | Command Prompt
Demo
10
Entering MS-DOS commands

Commands consist of
A single word
 Optional extra information
 e.g.
c:\>ver
c:\>ping www.playboy.com
c:\>ping www.bbc.co.uk

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The current directory

When using MS-DOS, it always places you in
a directory



“Everybody has got to be somewhere” (Eccles –
the Goon Show – circa 1954)
This is called the Current Directory
The command prompt tells you what the
current directory is


E.g. c:\windows\temp> ….
means current directory is \windows\temp
on the c: drive
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Finding out what is in the
current directory

Use the dir command

E.g. c:\>dir
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Disc
information
14
Directory name
15
Information
about the files
in this directory
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Date and time file last changed
p = pm
a = am
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<DIR> indicates these two items
are directories
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This file is named win2k.xpr
It is 189,624 bytes in size
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Total size of files in this directory
Number of bytes still available on
the disc
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Changing drive in MS-DOS


Demo
Use drive name (A:, C: etc)
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File handling in MS-DOS
Create and edit text files
edit
Display text files
type
Change current directory
cd
Make a new directory
md
Remove a directory
rd
Copy files from one directory
to another directory
copy
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Using edit



Demo
Creating text files
Editing text files
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Using copy




Demo
Using wildcards in copying
c:\>copy
*.txt
c:\temp
c:\>copy
*.*
c:\temp
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Using md to make directories



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Demo
Building this directory structure
c:\>md D
c:\>md A
c:\>cd D
c:\D>md B
c:\D>cd \
c:\>cd A
c:\A>md D
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Using cd






Demo
Moving up one level
c:\>cd A
c:\A>
c:\A>cd ..
c:\>
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Using cd with absolute and relative
paths






Absolute path: starts
with root
c:\>cd \A\D
c:\A\D>
Relative path: starts
from current directory
c:\A\D>cd ..\..\D
c:\D>
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Batch files



Batch files
Collecting batches of commands into
one command
Like a macro in other applications e.g.
Word, Excel
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A batch file example

What directory
structure does
this batch file
create:
cd \
md A
md B
cd A
md C
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A second batch file example

Write a batch file to
create this directory
structure:
cd \
md A
md B
md C
cd B
md D
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A third batch file example

Write a batch file to
create this directory
structure:
cd \
md D
md A
cd D
md B
cd \A
md D
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Operating systems: early 1980s

Apple Inc introduced first operating
system with a Graphical User Interface
(GUI)



Apple Lisa
Apple MacIntosh
Instructions issued using mouse clicks on
menus, and buttons
32
Operating systems: early 1980s
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Operating systems
Microsoft Windows family of operating
systems






Windows
Windows
Windows
Windows
Windows
Vista
95
98
2000
XP
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35
A brief survey of Microsoft
Windows Operating Systems

http://www.youtube.com/watch?v=y48rthTbrA8
Also - flv file present locally
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A brief survey of Microsoft
Windows Operating Systems


Microsoft Windows has two streams
Graphical front end to MS-DOS




Not based on MS-DOS




Windows
Windows 95
Windows 98
Windows 2000
Windows XP
Vista
Streams look the same but completely different
inside
37
Other PC Operating Systems

Linux operating systems







Red Hat Linux
SuSE Linux
Mandrakesoft Linux etc
Competitor to Microsoft
Based on Unix operating systems
Originally had only command line type
interfaces
Recent developments provide graphical
front ends
38