条件判断if 和 case...esac 判断（相当于switch）

1、if

if [];then

elif [];then

else

fi

ps:if和elif与[]中间也有空格！！

#!/bin/bashread -p “Please input(Y/N):” ynif [ “$yn” == “Y” ]||[ “$yn” == “y” ];thenecho “ok,continue”exit 0fiif [ “$yn” == “N” ]||[ “$yn” == “n” ];thenecho “oh,interrupt!”exit 0fiecho “I don’t know what your choice is” && exit 0

2、case

ps：匹配一个字符用 ?),  

匹配？或*要转义： bash sh09-2.sh \? 或者 bash sh09-2.sh “?”，script  里面用”?”)