shell计算二个日期中的天数

[code] 

1 #!/bin/sh

      2 #finename:132.sh
      3 #count the time of days form your birthday
      4 nowdays=$(date +%j)
      5 date -s 09/28/10
      6 birthday=$(date +%j)
      7 date -s 06/14/10
      8

      9 echo $(($birthday-$nowdays))

[/code]