Bash scripting - Sum of values = odd but echos even?

[Travercraig]

For some reason even if the sum of the two numbers is odd it echos thats it's even. I don't understand why. Can anyone idenify the problem?

 

Here is the code and a screenshot of the current output:

#!/bin/bashecho Enter value one:read valueOneecho Enter value two:read valueTwototal=$((valueOne+valueTwo))if ! [[ $valueOne =~ ^[0-9]+$ ]];    then        echo $valueOne "is not a number"fiif ! [[ $valueTwo =~ ^[0-9]+$ ]];    then        echo $valueTwo "is not a number"fiif [[ $total = %2!=0 ]]; then   echo $total "is an odd number"else   echo $total "is an even number" fi   

[alpenwasser]

For starters, there's a syntax error in your 'if' clause:

if [[ $total = %2!=0 ]]; then

Check how the modulo operator works, you should be able to spot the error fairly quickly

once you've looked that up (for example here: http://www.tldp.org/LDP/abs/html/ops.html )

The second thing you want to look for is bash and arithmetic evaluation of expressions,

as discussed here: http://stackoverflow.com/questions/2552130/bash-evaluate-a-mathematical-term

Once you've looked those two things up, you should be able to get this working I think.

[unijab]

#!/bin/bash

echo Enter value one:

read valueOne

echo Enter value two:

read valueTwo

total=$((valueOne+valueTwo))

mod=$(($total % 2))

if ! [[ $valueOne =~ ^[0-9]+$ ]];

then

echo $valueOne "is not a number"

fi

if ! [[ $valueTwo =~ ^[0-9]+$ ]];

then

echo $valueTwo "is not a number"

fi

if [ $mod != 0 ]; then

echo $total "is an odd number"

else

echo $total "is an even number"

fi

[Travercraig]

#!/bin/bashecho Enter value one:read valueOneecho Enter value two:read valueTwototal=$((valueOne+valueTwo))mod=$(($total % 2))if ! [[ $valueOne =~ ^[0-9]+$ ]];    then        echo $valueOne "is not a number"fiif ! [[ $valueTwo =~ ^[0-9]+$ ]];    then        echo $valueTwo "is not a number"fiif [ $mod != 0 ]; then   echo $total "is an odd number"else   echo $total "is an even number"fi

Hmm I've just realised that i only want the odd even to work if it's a number only. I can't figure that out either. If a letter is entered the odd even shouldn't echo.

[unijab]

 

#!/bin/bash

echo Enter value one:

read valueOne

echo Enter value two:

read valueTwo

 

 

if ! [[ $valueOne =~ ^[0-9]+$ ]];

    then

        echo $valueOne "is not a number"

        exit

fi

 

if ! [[ $valueTwo =~ ^[0-9]+$ ]];

    then

        echo $valueTwo "is not a number"

        exit

fi

echo -e "\n"

total=$((valueOne+valueTwo))

mod=$(($total % 2))

 

 

if [ $mod != 0 ]; then

   echo $total "is an odd number"

else

   echo $total "is an even number"

fi