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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
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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
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Organising files
Thousands of files can be held in
secondary storage
Organising the files is a job for the
operating system
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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
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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
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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
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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
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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
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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
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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
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Directory name
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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
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
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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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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
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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
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