shell控制语句

if语句

注意 if 后面要接 then,else后不需要，用fi表示结束if语句。

if [ condition ]; 
    then # do something
elif [ condition ]; 
    then # do something
else
    # do something
fi

---

case语句

case后面接变量+in，相当于C语言中的switch，

用value + )表示case的值，可以用|将多个运行值连接

"*"是在这里被视作通配符，可以用类似"Bob*")过滤出Bob开头的变量的情况，可以用单一个"*"表示C语言中default的情况，

用;;表示跳出case语句段，

用esac表示结束case语句

echo "This script will print your choice"
case $1 in
    "one" | "1" | "first")
    echo "You have chosen one"
    ;;
    "two" | "2" | "second")
    echo "You have chosen two"
    ;;
    *)
    echo "Error Please try Again"
esac

---

for循环

for var in item1 item2 ... itemN
do
    # do something
done

---

while循环

while condition
do
    # do something
done

---

until循环

until condition
do
    # do something
done