编写一个名为month的shell程序,其功能是将作为自变量的月份数据转换成英文的月份单词,并把运行结果存入用户主目录下mon文件中

下面程度中,加if那段程序什么意思,看不懂,还有最后exit2是什么意思．是不是exit1呀

iftest“$#”–ne1

then

echo“usage:monthd:git”

exit1

fi

case“$1”in

1)echoJanuary;;

2)echoFebruary;;

3)echoMarch;;

4)echoApril;;

5)echoMay;;

6)echoJune;;

7)echoJuly;;

8)echoAugust;;

9)echoSeptember;;

10)echoOctober;;

11)echoNevtrnber;;

12)echoDecember;;

*)echo“mustinrang1-12”

exit2;;

esac