Lecture 1 - Intro

Lecture 1
-

Intro

•
Course Overview

•
Linux BASH

•
Windows CMD/
Powershell

•
CLI
vs

GUI

•
Misc Useful Stuff

Operating System

•
Hardware
–

the physical
components of a system


•
Operating System
-

???



•
Software
–

the programs we
run


Operating System

•
Hardware
–

the physical
components of a system


•
Operating System
–

What is
this? What does it do?


•
Software
–

the programs we
run


Operating System

•
It’s a program


•
Essentially, allows users to
run other programs


•
More details later!

Operating Systems

•
DOS (“Disk Operating System”)
*

•
Windows: 3.1, 95, 98, NT, ME, XP,
Vista, 7





*Not quite true

Operating Systems

•
DOS (“Disk Operating System”)
*

•
Windows: 3.1, 95, 98, NT, ME, XP,
Vista, 7

•
Apple: Snow Leopard




*Not quite true

Operating Systems

•
DOS (“Disk Operating System”)
*

•
Windows 3.1, 95, 98, NT, ME, XP,
Vista, 7

•
Apple: Snow Leopard

•
Linux:
Ubuntu
/
Kubuntu
, Red Hat,
CentOS
,
Mandriva
, etc, etc


*Not quite true

Operating Systems

•
DOS (“Disk Operating System”)
*

•
Windows 3.1, 95, 98, NT, ME, XP,
Vista, 7

•
Apple: Snow Leopard
,
iOS

•
Linux:
Ubuntu
/
Kubuntu
, Red Hat,
CentOS
,
Mandriva
, etc, etc


*Not quite true

CLI
vs

GUI

•
CLI

–
“Command Line Interface”

–
Text
-
based communication with
operating system

•
GUI

–
“Graphical User Interface”

–
Image
-
based communication
with operating system

CLIs

Is this a CLI?

CLIs

THIS...is a CLI!

CLIs

•
Predate GUIs


•
Text only

–
No mouse!


•
Still exist today!

–
Why?

CLIs

•
Predate GUIs


•
Text only

–
No mouse!


•
Still exist today!

–
Still very useful

GUIs

GUIs

•
More natural interface

–
2
nd

generation “point and click”
*


•
Raster
-
based feedback

–
Images make sense to us

–
New desktop managers
removing menu
-
style interfaces


*See “Samuel Colt”

CLI
vs

GUI

•
What can GUIs do that CLIs
can’t do?

CLI
vs

GUI

•
What can GUIs do that CLIs
can’t do?

–
Nothing!

CLI
vs

GUI

•
What can GUIs do that CLIs
can’t do?

–
Nothing!


–
All of this class can be done
without a GUI.

CLI
vs

GUI

•
What can GUIs do that CLIs
can’t do?

–
Nothing!


–
All of this class can be done
without a GUI.


–
90%+ of this class should be
done without a GUI.

CLIs

•
We will be using:

–
BASH


–
CMD

Powershell

Events

•
Modern OSs are event
-
driven

–
Keyboard presses


–
Mouse clicks


–
BOTH up and down
clicks/presses

Events

•
Every event has a time
-
stamp….why?

Events

•
Every event has a time
-
stamp….why?

–
So we can order our actions

–
OS might have a queue built up

–
Some events may need delayed
action

–
Etc, etc, etc

Events

•
Why record events?

–
Actions!

•
Every time YOU do something,
you probably want the OS to do
something.

Desktop Environments

•
Windows

–
Various “Windows
Explorer”s

•
Linux

–
KDE, Gnome, etc, etc

•
OS
-
X

–
Heck if I know…can probably
run Linux DEs.

–
CEG233: Introduction to
Windows and Linux
.

Desktop Environments

•
GUI interface to the OS

•
“Same $#!7, different DE”

–
Open folders

–
Drag & drop

–
Execute programs

–
Change system settings

–
Cut & paste

–
Highlighting

–
Etc, etc

Shells

•
CLI interface to the OS

–
This is the one we care about

•
Windows

–
CMD,
Powershell

•
Linux

–
cshell
,
rshell
, BASH, etc

Shells

•
Windows

–
CMD

•
“Traditional” shell

–
Powershell

•
Newer shell

•
PS scripting is much closer to
BASH scripting


Shells

•
Linux

–
sh
: Bourne Shell

–
ksh
:
Korn

Shell

–
rsh
: Remote Shell

–
csh
: C Shell

–
bash: Bourne
-
again Shell

Directory Structure

Dear students,


Please give the bearded man

a moment to draw pretty

pictures. They will help you!


Your Instructor

Picture topics

•
Root (of the file system)


–
Explicit in Linux


–
“Hidden” in Windows

•
‘C drive’ is NOT always the main
drive (mine used to be ‘F drive’)


Picture Topics

•
PWD/CWD

–
‘
P
resent’ or ‘
C
urrent’
W
orking
D
irectory

–
“Where am I at (in the tree)?”


Picture Topics

•
Absolute paths

–
Explicitly state exactly where
the file is

•
Earth
-
> North America
-
> USA
-
>
Ohio
-
> Dayton
-
> WSU
-
> Joshi


Center
-
> JC182


Picture Topics

•
Relative paths

–
Collectively agree that we’re in
some spot, and go from there

•
.
-
> Joshi Center
-
> JC182


Picture Topics

•
.

–
“This” directory

–
Used to execute commands in
current directory (coming up
later)

•
..

–
Parent directory


Mounting

•
We rarely have just one
storage unit

–
CDs/DVDs

–
More hard drives

–
Thumb drives

–
Network storage

•
In order to access them, we
need to add them to the tree

Windows File System

•
C:
\
Program Files

•
C:
\
Program Files (x86)

–
Where user programs are
installed


•
C:
\
Windows

–
Where the OS and essential
programs are


Windows File System

•
C:
\
Users & …

•
C:
\
Documents and Settings

–
Home Directories

•
Your own “private” storage real
estate.

•
Each user account has one (by
default)

•
They might exist for users that
don’t‘

–
Users can get deleted and still leave
their home directory


Linux File System

•
/bin

–
Contains commands useful to
all users (cat,
cd
, echo,
ls
, …)

•
/boot

–
(Almost) everything needed to
boot the OS

•
/dev

–
List of all devices on the system

Linux File System

•
/etc

–
System configuration files

•
/home

–
Self
-
explanatory

•
/lib

–
Contains kernel modules and
libraries needed by commands
in /bin and /
sbin

Linux File System

•
/media

–
“New” mount point

•
/
mnt

–
“Old” mount point

•
/opt

–
Intended

for 3
rd

party software

•
/proc

–
Somewhat unique…ignore it

•
Virtual file system in its own right

Linux File System

•
/root

–
Home directory of ‘root’ account

•
/
sbin

–
Commands used for
administration

•
/
usr

–
Contains user binaries, libraries,
header files, help docs, etc

•
There’s more in the weeds...

Permissions

•
Files

–
Read: Can I see the contents?


–
Write: Can I change the
contents?


–
Execute: Can I run the contents
as a script or program?

•
Not applicable to “data” files

Permissions

•
Directories

–
Read: Can I list the
names

of
the files in the directory?

•
NO FURTHER INFO


–
Write: Can I add/remove files
to/from directory


–
Execute: Can I list the directory
and related info?


Permissions: UGO

•
User

–
Who “owns” the file?

•
Group

–
What collection of folks allowed
to do something with the file

•
Other

–
If you aren’t one of the above,
you’re this one.

‘
ls

–
l’ Example

drwxr
-
xr
-
x 10 admirald7s Installers 4096 2011
-
10
-
12 11:33 jdk1.6.0_27

‘
ls

–
l’ Example

d ……………………...
-
> File type (in this case, a directory)

•
Could be ‘
-
’, ‘d’, ‘c’, ‘l’, ‘b’

rwxr
-
xr
-
x ……………
-
> permissions

•
User, then Group, then Others

10 …………………….
-
> Number of sub
-
directories and links


admirald7s …………
-
> user


Installers ……………
-
> group


4096 ………………..
-
> Size of directory

•
Only things in the
immediate

directory (not recursive)

2011
-
10
-
12 11:33 …..
-
> Timestamp of last modification



jdk1.6.0_27 …………
-
> Name of the file/directory

Basic commands

•
bash


Bourne
-
Again Shell

•
bg


background

•
cat


show each file in sequence

•
chmod

change file permission

•
chown

change the owner of a file

•
cmp


compare two files

•
df


show mounted volumes, etc

•
diff


show differences between two files

•
du


show disk usage

•
echo


echo
/print arguments given

•
emacs

the all
-
powerful text/binary editor

•
env


lists the current environment variables

•
fg


foreground

•
file


guess what kind a file is

Basic Commands

•
grep


print lines matching a pattern

•
kill


kills a running program

•
ln


creates a link between two files; try

ln

–
s

•
ls


list contents of directory; try

ls

–
lisa

•
ltrace


show library calls made

•
links


WWW/News/Mail browser

•
ps


shows current processes

•
set


set
/get the value of shell variables

•
sftp


transfer files securely to/from a remote


machine

•
source

execute the commands in a file

•
ssh


remote login securely

•
strace

show sys calls made

•
time


times the following command

Basic Commands

•
top


like
ps
, but with continuous updates

•
umask

get/set the file mode creation mask

•
vi


text editor

•
w


who is on the system

•
wc


word count, etc

•
There are more!



•
Green are easy commands


•
Black are medium commands


•
Red are commands that are or can be
dangerous

is you
don’t know what you’re doing.




Learning Basic
Commands

•
NEVER execute unknown
commands

–
Research the command first


•
Use the man pages

–
e.g., “man
wc
”, “man time”, or
even “man
man
”

Commands fodder

•
Whitespace

–
Spaces, tabs, etc


•
Tokens

–
Not for arcade games



Environmental
Variables

•
Variables that help the OS

–
PATH

–
LD_LIBRARY_PATH

–
USERNAME

–
TEMP

& TMP

–
OS

–
Etc

•
No different than ‘
int

x = 5;’

PATH

•
‘
ls’

is just another
program/script


•
When we type ‘
ls’
, how does
the system know where that
command is?

PATH

•
‘
ls’

is just another
program/script


•
When we type ‘
ls’
, how does
the system know where that
command is?

–
‘PATH’ variable

Misc Stuff I Forgot

•
File extensions

–
Windows uses them to
determine file type


–
Linux doesn’t care about them
at all

RVH’s Lab
Disclaimer(s)

1.
Labs can be vague

2.
This is semi
-
intentional

3.
RVH will give piece
-
meal
help

4.
You WILL have to figure
things out on your own

General Lab
Requirements

•
No output, no credit!


•
Make it easy to figure out
what text goes with which
step

Lab 2 Pre
-
Material

•
Get a flash drive

–
At least 4GB

–
Empty (or with contents you
don’t care about)

–
If you come with a U3 drive, you
will walk away with a non
-
U3
drive.

Lab 1 Material

•
By ‘use’, I mean ‘use in a
meaningful way’.


•
“.
bashrc
” does NOT exist
on these systems until you
create it.