r/Dailyprogrammer Challenge #201 Easy

rdp_201_easy.sh

##################################################
#  r/Dailyprogrammer Challenge #201 Easy         #
#   coded by Michael Repper                      #
#   query [a * t ] gridoodle [ d * o * t ] com   #
##################################################

#####################################################################################
#  Takes 1 or 2 dates as parameters. The dates should strings be in the format:     #
#    "YYYY-mm-dd" "YYYY-mm-dd" OR "YYYY-mm-dd"                                      #    
#  If only one date is supplied, the days are calculated from the current date.     #
#  If two days are supplied, it calculates the days between them.                   #
#####################################################################################

function days_from ()
{
    if [ $# -gt 1 ]
    then
        date_1=($1)
        date_2=($2)
    else
        date_1=`date +%Y-%m-%d`
        date_2=($1)
    fi
    result=$(echo $((($(date -d $date_1 +'%s') - $(date -d $date_2 +'%s'))/60/60/24)))
    if [[ $result -lt 0 ]]
    then
        ((result*=-1))
    fi
    echo $result "days from" $date_1 "to" $date_2

}

days_from "2012-01-01" "2019-10-12"
days_from "2020-01-01"