[SOLVED] difference between two dates in days in shell

Issue

I have two variables date1=2023-10-08 and date2=2023-10-09 I want to calculate the difference between the two in days , I'm trying with:

 DIFF=$(( ($date2 - $date1) / (60 * 60 * 24) ))
if [ $DIFF -eq 1 ]
    then
        echo "one day ago.."
    else
        echo "many dayzz"
fi

I'm getting this error:

(2023-10-09: value too great for base (error token is "09")

Solution

Bash arithmetic cannot process date within this format. Dates must be converted to integers with a tool such as date. Using GNU date's %s, one can compute the difference with

$(( ($(date -d "$date2" "+%s") - $(date -d "$date1" "+%s")) / 86400 ))

Answered By - Loïc Reynier

Answer Checked By - Timothy Miller (WPSolving Admin)