Linux Bash Scripting ,Bash Scrip examples

Lab13: Bash Scripting
Lab Tasks:
1. Write a bash script to find out the biggest number from given three numbers. The numbers are supplied as command line argument to the script. Print an error message if sufficient arguments are not supplied.

#!/bin/bash

if(($#!=3));

then

    echo ERROR: Please specify exactly three number as argument;

    exit 1;

else

{

    if [ $1 -gt $2 ]; then

    if [ $2 -gt $3 ]; then

    echo $1 is biggest;

    elif [ $1 -gt $3 ]; then

    echo $1 is biggest;

else

echo $3 is biggest;

fi

else

    if [ $2 -gt $3 ]; then

    echo $2 is biggest;

    else

    echo $3 is biggest;

fi

fi

}

fi

2. Write a bash script to find out the volume of a pizza. Both the radius and height of the pizza should be input by the user and can be real numbers i.e numbers like 3.14259 (Hint: Use read and bc utilities).

#! /bin/bash

echo "Please Enter Height of Pizza"

read height

echo "Please Enter Radius of Pizza"

read radius

result=$(echo 3.14259*$radius*$radius*$height | bc)

echo "Volume of Pizza is =$result"

3. Write a bash script that calculates the factorial of a number given as the argument, using a while or until loop.

#! /bin/bash

if [ $# -ne 1 ]; then

echo 'Only one argument is required'

else

num=$1

fac=1

while [ $num -gt 1 ]

 do

 fac=$(( $fac*$num ))

 num=$(( $num - 1 ))

 done

echo "Factorial is $fac"

fi

4. Write a bash script that checks if the apache and cron daemons are running on your system. If apache/cron is running, the script should print a message like, "Apache/Cron is Alive!!!" (Hint: Use ps to check on processes).

SERVICE='cron'

if ps ax | grep -v grep | grep $SERVICE > /dev/null

then

   echo "Cron is Alive!!!!!!!!!"

else

   echo "$SERVICE is not running"

fi

apachee='apache'

if ps ax | grep -v grep | grep $SERVICE > /dev/null

then

   echo "Apache is Alive!!!!!!!!!"

else

   echo "$SERVICE is not running"

fi

Bonus: Write a script that calculates the factorial of a number given as the argument, using a recursive function.

#!/bin/bash

factorial()

{

 if [ $# -ne 1 ];then

 echo "Error: Only one argument is required "

 exit 1

 fi

 local i=$1

 local f

 declare -i i

 declare -i f

 [ $i -le 2 ] && echo $i || { f=$(( i - 1 ));f=$(factorial $f);f=$(( f * i ));echo $f;}

}

factorial $1