## Shell script to read 5 digit number and calculate the sum of digit

in Categories Shell Math last updated April 4, 2008
```#!/bin/bash
# Shell script to read 5 digit number and calculate the sum of digit
# -------------------------------------------------------------------------
# Copyright (c) 2005 nixCraft project <http://cyberciti.biz/fb/>
# -------------------------------------------------------------------------
# This script is part of nixCraft shell script collection (NSSC)
# -------------------------------------------------------------------------

echo -n "Enter numnber : "

# find out length of string using wc -c command
len=\$(echo \$n | wc -c)

# remove \n i.e. new line character
len=\$(( \$len - 1 ))

# use loop to go throug all digit one by one and calculate sum of digit on fly
for (( i=1; i <= \$len; i++ ))
do
sum=\$(( \$sum + \$(echo \$n | cut -c \$i) ))
done
echo "Sum of \$n is \$sum"```

## Shell Script Calulate Area and Circumference of Circle

in Categories Shell Math last updated April 4, 2008

A circle is one of the simple shapes of Euclidean geometry. It is the locus of all points in a plane at a constant distance, called the radius, from a fixed point, called the center. Through any three points not on the same line, there passes one and only one circle.

A diameter is a chord passing through the center. The length of a diameter is twice the radius. A diameter is the largest chord in a circle.

Circles are simple closed curves which divide the plane into an interior and an exterior. The circumference of a circle is the perimeter of the circle, and the interior of the circle is called a disk. ## Sample Shell Script To Calculate Area and Circumference of Circle

```#!/bin/bash
# Shell script to calulate area and Circumference of circle.
# It take radius of a circle as input.
# -------------------------------------------------------------------------
# Copyright (c) 2005 nixCraft project <http://cyberciti.biz/fb/>
# -------------------------------------------------------------------------
# This script is part of nixCraft shell script collection (NSSC)
# ----------------------------------------------------------------------
# Lesson on Circumference of a Circle :
#  Visit http://www.mathgoodies.com/lessons/vol2/circumference.html
echo -n "Enter the radius of a circle : "

# use formula to get it
area=\$(echo "scale=2;3.14 * (\$r * \$r)" | bc)

# use formula to get it
d=\$(echo "scale=2;2 * \$r"|bc)
circumference=\$(echo "scale=2;3.14 * \$d"| bc)

echo "Area of circle is \$area"
echo "Circumference of circle is \$circumference"```

## Shell Script to read price of an article and calculate discount

in Categories Shell Math last updated April 4, 2008
```#!/bin/bash
# Script to read price of an article. If the price is less than 100
# then display "No discount" else give a discount of 10%. Display
# the price of article after discount
# -------------------------------------------------------------------------
# Copyright (c) 2005 nixCraft project <http://cyberciti.biz/fb/>
# -------------------------------------------------------------------------
# This script is part of nixCraft shell script collection (NSSC)
# -------------------------------------------------------------------------

echo -n "Enter price of an article : "

if [ \$price -lt 100 ]
then
echo "No discount "
d=0 # 0 means no discount
else
echo "10% discount "
d=\$(( \$price  * 10 / 100 )) # 10% discount
fi
# how much user need to pay? after discount
pay=\$(( \$price - \$d ))
echo "You need to pay INR. \$pay"```

## Script to display sum of two number and to do calculations such as +, -, / etc

in Categories Shell Math last updated April 15, 2008
```#!/bin/bash
# Script to display sum of two number and to do calculations such as +, -, / etc
# -------------------------------------------------------------------------
# Copyright (c) 2005 nixCraft project <http://cyberciti.biz/fb/>
# -------------------------------------------------------------------------
# This script is part of nixCraft shell script collection (NSSC)
# ----------------------------------------------------------------------
echo "**** My calculator ****"
echo "M A I N - M E N U"
echo "1. Multiplication"
echo "2. Subtraction"
echo "3. Remainder"
echo "4. Divide"

echo -n "Enter your first number : "
echo -n "Enter your second number : "

if [ \$choice -eq 1 ]
then
answer="\$n1 x \$n2 = \$(( \$n1 * \$n2 ))"
elif [ \$choice -eq 2 ]
then
answer="\$n1 - \$n2 = \$(( \$n1 - \$n2 ))"
elif [ \$choice -eq 3 ]
then
answer="\$n1 % \$n2 = \$(( \$n1 % \$n2 ))"
elif [ \$choice -eq 4 ]
then
answer="\$n1 / \$n2 = \$(( \$n1 / \$n2 ))"
else
echo "Sorry please select number between 1-4 only"
exit 1
fi

## Shell script to read 3 numbers and find the greaters of the three

in Categories Shell Math last updated April 4, 2008
```#!/bin/bash
# Shell script to read 3 numbers and find the greaters of the three
# -------------------------------------------------------------------------
# Copyright (c) 2005 nixCraft project <http://cyberciti.biz/fb/>
# -------------------------------------------------------------------------
# This script is part of nixCraft shell script collection (NSSC)
# ----------------------------------------------------------------------
echo -n "Please enter three numbers (separate number by space) : "
# compare a with b and c. Note -a is logical and operator
if [ \$a -gt \$b -a \$a -gt \$c ]
then
big=\$a
elif  [ \$b -gt \$a -a \$b -gt \$c ] # compare b with a and c
then
big=\$b
elif  [ \$c -gt \$a -a \$c -gt \$b ] # compare c with a and b
then
big=\$c
elif [ \$a -eq \$b -a \$a -eq \$c -a \$b -eq \$c -a \$c -eq \$b ] # see if all of them are equal or not
then
big="All three numbers are same (equal)"
else # something must be wrong if we are here, like one of number is character such as 'A'
big="Can not guess greaters of three numbers"
fi
# display result
echo "Result : \$big"```

## Shell Script Convert Fahrenheit to Celsius Temperature ( Celsius to Fahrenheit Temperature )

in Categories Decision Making, Shell Math last updated February 3, 2009

Explains how to write temperature conversion formulas shell script to convert Fahrenheit to Celsius or vise versa.

## Shell Script to read the base and height of a traingle and find its area

in Categories Shell Math last updated April 3, 2008

Calculating the area of a triangle is an elementary problem encountered often in many different situations. The best known, and simplest formula is Where S is area, b is the length of the base of the triangle, and h is the height or altitude of the triangle. The term ‘base’ denotes any side, and ‘height’ denotes the length of a perpendicular from the point opposite the side onto the side itself.

```# Shell program/script to read the base and height of a traingle and find its area
# -------------------------------------------------------------------------
# Copyright (c) 2005 nixCraft project <http://cyberciti.biz/fb/>
# -------------------------------------------------------------------------
# This script is part of nixCraft shell script collection (NSSC)
# -------------------------------------------------------------------------
# Formula info: http://www.mste.uiuc.edu/dildine/heron/triarea.html

# Area=(1/2) x Base x Height
echo -n "Enter base of a triangle : "

echo -n "Enter height of a triangle : "
# calculate it and display back
area=\$(echo "scale=2;(1/2) * \$b * \$h"|bc)
echo "Area of a triangle is \$area"```

## Shell Script to display current date, calendar, and the number of user logged

in Categories Academic last updated April 3, 2008

This script use the concept of command substitution. It allows allows the output of a command to replace the command name. There are two forms:

\$(command)

or

`command`

Bash shell performs the expansion by executing command and replacing the command substitution with the standard output of the command, with any trailing newlines deleted. Embedded newlines are not deleted, but they may be removed during word splitting.

For example you can execute date command to display todays date and then set a variable called NOW:
`NOW=\$(date)`
or
`NOW=`date``
To display back variable value simply run echo command:
`echo \$NOW`

## Sample Shell Script

```#!/bin/bash
# Shell script to display current date, calendar, and the number of
# user logged.
# -------------------------------------------------------------------------
# Copyright (c) 2005 nixCraft project <http://cyberciti.biz/fb/>
# -------------------------------------------------------------------------
# This script is part of nixCraft shell script collection (NSSC)
# ----------------------------------------------------------------------
echo "Today is \$(date)"
echo ""

echo "Calendar :"
cal

echo "Number of users currently logged : \$(who | wc -l)"```

## Shell Script to ask user his / her name and then display it with a G’Day/Good morning message

in Categories Academic last updated April 3, 2008

This script greets user with a message. Then it displays prompt asking user her name. Once name entered it will display Gooday message using echo command.

read statement will read one line from the user (keyboard) or from file and store it to a variable called yourname.

```#!/bin/bash
# Shell Script to ask user his/her name and then display it with a
# GoodDay/Good morning message
# -------------------------------------------------------------------------
# Copyright (c) 2005 nixCraft project <http://cyberciti.biz/fb/>