CODEWITHSUNDEEP
linuxbashshell
Jimmy
Jimmy

Reputation: 15

Linux Shell if-statements

I am trying to write a script to add integers together. My first script works to add numbers

for number in $@; do
sum=$(($sum + $number))
done

echo $sum

Now I am trying to write an if statement that checks if $number is an valid integer and if not display an error message and kill the script. 

if [ -z $number]; then
sum=$(($sum + $number))
else
echo $number
echo "Sorry, $number is not a number"
exit
fi

I have been trying to figure this out for a few hours and keep getting stuck and help would be nice

Upvotes: 0

Views: 278

Answers (2)

Eric Renouf
Eric Renouf

Reputation: 14520

the -z test will just test of the variable is empty (zero length) or not. If you want to know that is has an integer you could use a regex match like

if [[ $number =~ ^-?[0-9]+$ ]]; then
    sum=$((sum + number))
else
    echo "Sorry, $number is not a number"
    exit
 fi

Upvotes: 2

Gene
Gene

Reputation: 351

The -z operator doesn't check if the string is a number, it checks if the length of the string is zero.

There isn't an operator to check if a string is an integer, however there are several ways to do this in bash. The answers on this previous discussion should be helpful.

Upvotes: 2

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