shell if用法

      1 #!/bin/sh
      2 echo "Is it morning? please answer me"
      3 read timeofday
      4 
      5 if [ $timeofday="yes" ];   if与 [] 之间必须有空格
      6  then
      7   echo "good morning"
      8 else
      9   echo "good afternoon"
     10 fi
     11 exit 0
     12