SHELL指令碼每月最後一天判斷

#!/bin/bash


####函式定義
function monBigorSmall()
{
big_month=(1 3 5 7 8 10 12)
small_month=(4 6 9 11)
year=$(echo $1|cut -c 1-4)
month=$(echo $1|cut -c 5-6)
day=$(echo $1|cut -c 7-8)


for bvar in ${big_month[@]}
do
   if [ $bvar -eq $month ]
   then
      echo 31
   fi
done


for svar in ${small_month[@]}
do
   if [ $svar -eq $month ]
   then
      echo 30
   fi
done


iyear=$((10#${year}))
imonth=$((10#${month}))


if [ $imonth -eq 2 ]
then
    if [ $(($iyear % 4)) -eq 0 -a $(($iyear % 100)) -ne 0 ] || [ $(($iyear % 400)) -eq 0 ]
    then
        echo 29
    else
        echo 28
    fi
fi

}