一、shell实现

[root@localhost test2]# vi month_lastday.sh

#/bin/bashcase $1 in1|3|5|7|8|10|12) echo last_day=31 ;;4|6|9|11)        echo last_day=30 ;;2)               echo last_day=28 ;;*)               echo "ERROR!" ;;esac[root@localhost test2]# chmod 755 month_lastday.sh [root@localhost test2]# ./month_lastday.sh 1last_day=31[root@localhost test2]# ./month_lastday.sh 2last_day=28[root@localhost test2]# ./month_lastday.sh 4last_day=30[root@localhost test2]# ./month_lastday.sh 55ERROR!