Comments on: Shell Script Examples: case, count, for, if, while and User input

By: Thorsten

Thorsten — Sun, 27 Nov 2011 08:45:11 +0000

Here is a non complete sample of how you can solve the problem. Please observe that bc is used instead of expr for calculations with decimals. The scale variable tells bc how many decimals to use when computing the numbers.

#!/bin/bash
clear
echo -n “First number: ”
read N1

echo -n “Second number: ”
read N2

echo -n “Third number: ”
read N3

echo ”
A Add
M Multiply
V Average
”
echo -n “Please choose A, M or V: ”
read JOB

case $JOB in
a|A)
expr $N1 + $N2 + $N3
;;
m|M)
expr $N1 \* $N2 \* $N3
;;
v|V)
TOTAL=`expr $N1 + $N2 + $N3`
echo “scale=2;$TOTAL / 3 ” | bc -l
;;
*) echo wrong choice;;
esac

By: Thorsten

Thorsten — Sun, 27 Nov 2011 08:18:38 +0000

I would use “read” to get user input. Example:
#!/bin/bash
read USERINPUT
echo $USERINPUT

For the math bit there is a nifty utility called expr. Example:
expr 12 + 12

will return the result of 24

I hope that this helps you
/thorsten

By: bigron

bigron — Sat, 26 Nov 2011 23:23:55 +0000

Hi i would like to know how to write a math script that ask the user for three numbers. gives the user three options to choose from: add,multiply and average. I also would like to use a case statement to make it work, save as one function.

Thanks.