I find this amazing small piece of code in this question:
datediff() {
d1=$(date -d "$1" +%s)
d2=$(date -d "$2" +%s)
echo $(( (d1 - d2) / 86400 )) days
}
Does being on the site make this content open source and if yes what is the license of it ?
In this case this is an answer but I ask myself the same for question.