Linux Essentials, A Sample Shell Script

Front 1

what is lilo

Back 1

its a boot loader

Front 2

what are 3 components to a linux machine GUI

Back 2

X server
Window Manager =
(Beryl, ice, sawfish)
Desktop environment =
(all point and click functionality...KDE, GNOME, CDE)

Front 3

play around with all your options, settings and everything you can manipulate, if your worried about breaking something run linux from a LIVE CD.

Back 3

Or use a VMWARE player and Vmware image of your choice of linux. (a vmware image is called a Vmware application in vmware terminology and called a template in Oracle virtual machine terminology as of 2009)

Front 4

to mess with your linux GUI on a granual level you must use

Back 4

Xconfigurator
(must be a capitol 'X' and You must be a superuser)

Front 5

what does Xconfigurator change

Back 5

changes the xf86 config file

Front 6

where is the xf86config file

Back 6

usually in /user/X11R6/lib/X11 or /ect/X11
go to XFree86 or view the readme file in the X11 directory

Front 7

Having trouble with resolution video card settings and such. what do I edit

Back 7

cd /ect/X11
vi X11
(or)
su (or sudo) nautilus
(browse to the X11 file and edit it accordingly)

Front 8

monitor is not in your list in Xconfigurator

Back 8

choose a custom monitor and enter your color depth and refreshrate (don't choose a refresh too high or a resolution too high just yet)

Front 9

what is shell scripting

Back 9

mini-program that has multiple linux commands stringed together. resolves repetitive tasks. sort of like a Macro in Windows.

Front 10

every shell script ends in

Back 10

.sh

Front 11

all shell scripts start with a "shabang" what is this

Back 11

#! <-- that is a shabang...the sharp symbol followed by the exclamation point...Sha# _ Bang!

Front 12

what comes after the shabang.

Back 12

the path to the shell script you want to use...for instance.
#! /bin/bash

Front 13

any line that starts with the sharp sign (#) is what?

Back 13

# a comment or note to the reader, author, update history ect...

Front 14

show /print on your screen this statement:
"I am writing a short script"

Back 14

echo "I am writing a short script"
echo "I am bashman, ahh ha ha"

Front 15

now run your script after you have saved it in your script editor

Back 15

bash yourfirstscript.sh
or
./yourfirstscript.sh

Front 16

You just got a 'permission denied' error when trying to run your script. What do you do?

Back 16

here you must change the file to execute permissions. with the following command

chmod 755 yourfirstscript.sh
or
chmod rwe yourfirstscript.sh
(if you don't know what this is refer to my other flash cards containing user permissions)

Front 17

what is a variable

Back 17

data or information that will be filled into the script like a name or number. Or like the answer to a question in a program.

Front 18

insert a variable into your script

Back 18

#! /bin/bash
echo "Hello $1."
When you run this script by typing...
./yourscript.sh Chris ...it will print to the screen Hello Chris

Front 19

local variables are just a name assigned or an alias for a bunch of numbers...add a couple of local variables together.

Back 19

#! /bin/bash
NUMBER1=124
NUMBER2=345

let NUMBER3=$NUMBER1+$NUMBER2
echo "the answer is $NUMBER3"

Front 20

Is bash syntax and case sensitive?

Back 20

YeS

Front 21

what is the dollar sign ($) for?

Back 21

it tells bash that you gave a name to a bunch of numbers and want to put them here for manipulation or adding, subt. whatever....with other variables.
for instance: varible_number=123, or the number 123 to be inserted here ($).
$varible_number ...will give the number 123 in it's place.
$varible_number + $another_number ...will add these bunch of numbers together.

Front 22

using an 'if' 'else' conditional statement need a couple things.

Back 22

if [ ].....brackets
.....$1 first vairable
if [$# ] .....number of variables $#

then echo '' sentense $0 script''...variable to enter in a sentence
exit.....the exit command
fi ...the end of the 'if' 'then' statement.

Front 23

sample if-then statement to run the
du command in linux.
this command reminds the user to enter a user name if they have not done so. ELSE (if they did add a user name). It will execute the du command and state USERNAME is using ???? space in kilobytes.
the 'cut' command can be explained later...it is for aesthetic purposes and removes some text that is normally given with the du command.

Back 23

if [$# -lt 1]
then
echo "you need at least 1 user name to the $0 script"
exit
fi
cd /home/$1
SPACE='du -s | cut -f 1'
echo "$1 is using $SPACE kilobytes"

Front 24

what is in a bash 'While' Loop script

Back 24

while [$# -ge 1 ]
do
(put your code here)
shift (useful in a while loop)
done

Front 25

knowing C++ will help tremendously for bash. but the code is way different. name some functions in linux

Back 25

[$# -lt 1]
if the variable is less than 1
[$# -gt 2]
if the variable is greater than 2
[$# -ge 3]
if the variable is greater than or equal to 3

Front 26

where is the lilo boot loader file

Back 26

cat /etc/lilo.conf
or /ect/lolo.conf.anaconda
depending on your flavor of Linux

Front 27

sda
sdb
sda1
sdb2
hda
hdb
hda3
hda4
What are these?

Back 27

scsi disk one
scsi disk two
scsi disk one partition 1
scsi disk two partition 2
hard disk one
hard disk two
hard disk one partition 3
hard disk one partition 4

Linux lables disks as 'sd' for scsi, and
'hd' for hard disk...

a, b, c, ~z for additional disks of the same kind. followed by 1,2,3 ~99 for partitions on that disk.
sd_a, sdb, sdc

Front 28

man lilo
or man GRUB

Back 28

these are popular boot loaders. and work very similar. Grub seems to be more advanced and the preference for todays Ubuntu and Mandriva distros. (2009) but the concept is the same. Edit their ".conf" files for advanced boot configurations. multiple OS boots and so on. Or create a Boot disk with Grub.