CODEWITHSUNDEEP
bashshellunix
magalenyo
magalenyo

Reputation: 383

Bash: How to extract digits from a number

So I introduce a number to my script, just like this:

./script 795

and I'd like to extract each digit from that number and check if it's smaller than 7. Something like:

if [ 7 -le 7 ]
then 
echo "The first digit is smaller than 7"

I'd like to know how to extract each digit.

Upvotes: 5

Views: 5856

Answers (1)

Tom Fenech
Tom Fenech

Reputation: 74705

You can use a substring to extract the first character of the first argument to your script:

if [ ${1:0:1} -lt 7 ]; then
    echo "The first digit is smaller than 7"
fi

To do this for each character, then you can use a loop:

for (( i = 0; i < ${#1}; ++i )); do
    if [ ${1:$i:1} -lt 7 ]; then
        echo "Character $i is smaller than 7"
    fi
done

Notes that I've changed -le (less than or equal) to -lt (less than) to make your message correct.

Upvotes: 6

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