Selection And Repetition Part II

Last time we already learn about selection and repetition using test and operator
right now we will use if,case, for,while, until and select

if

below is the example

#!/bin/bash

key="bash";
read -s -p "Your Password : " pass
if [ $pass==$kunci ]; then
    echo "Success, You are able to login"
else
    echo "Sorry, Your password is wrong";
fi

below is the result

[elvin@TestBed$]./if2
Password anda : bash
Success, You are able to login
[fajar@linux$]./if2
Password anda : Bash
Sorry, Your password is wrong

else will be execute if the condition is not being fulfilled

below is the example of nested if

#!/bin/bash

clear
echo "Menu of the day";
echo "---------------";
echo "1. Noodle    ";
echo "2. Satay     ";
echo "3. Exit      ";
read -p "Your choose [1-3] :" pil;

if [ $pil -eq 1 ]; 
then
   echo "How Many =";
   read sum
   let pay=sum*1500;
elif [ $pil -eq 2 ]; 
then
   echo "How Many =";
   read sum
   let pay=sum*2000;
elif [ $pil -eq 3 ]; 
then
   exit 0
else
   echo "Sorry, Your choose is not available"
   exit 1
fi

echo "Total Payment = Rp. $pay"
echo "THX"

below is the result

[elvin@TestBed$]./if3
Menu of the day
---------------
1. Noodle   
2. Satay 
3. Exit    
Your choose[1-3] :2

How Many = 2

Total Payment = Rp. 4000
THX

case

the function of case is same like if. for sometimes condition, case is more efficience than if command

below is the example

#!/bin/bash

clear
echo -n "Please input your menu :";
read menu;

case $menu in
    noodle | kwetiau | bihun ) echo "$menu is chinese food"
                  break   
                              ;;
    steak | pizza | sandwich ) echo "$menu is western food"
                  break
                  ;;
    *) echo "$menu is not being defined"
                  break
                  ;;
esac

below is the result

[elvin@TestBed$]./cs1
Please input your menu : noodle 
noodle is chinese food

for

for statement is using for repetition

below is the example

#!/bin/bash

for number in 1 2 3 4 5;
do
   echo "number=$number";
done

below is the result

[elvin@TestBed$]./for1
number=1
number=2
number=3
number=4
number=5

while

while statement will do the command as long as the condition is true

below is the example to print odd number

#!/bin/bash

i=1;
while [ $i -le 10 ];
do
  echo "$i,";
  let i=$i+2;
done

below is result

[elvin@TestBed$]./wh1
1,3,5,7,9,

until

until statement will do the command if the condition is false

below is the example

#!/bin/bash

i=1;
until [ $i -gt 10 ];
do
  echo $i;
  let i=$i+1
done

below is the result

[elvin@TestBed$]./ut
1,2,3,4,5,6,7,8,9,10,

select

below is the example

#!/bin/bash
#menu1

clear
select menu
do
  echo "you choose $REPLY is $menu"
done

below is the result

layout:
[elvin@Testbed$]./menu1 Slackware Redhat Mandrake
1) Slackware
2) Redhat
3) Mandrake
 #? 1
you choose 1 is Slackware