shell——流程控制

1.if else

1.1 if

if condition
then
command1
command2
...
fi

1.2 if else

if condition
then
command1
command2
...
else
command3
fi

1.3

if condition1
then
command1
elif condition2
then 
command2
else
command3
fi

if else语句经常与test命令结合使用，如下：

2.for

for var in item1 item2 item3
do
command1
command2
done

3.while

while condition
do
command
done

4.until

until 循环执行一系列命令直至条件为 true 时停止。

until condition
do
command
done

5.case

case val in
pattern1)
command1
;;
pattern2)
command2
;;
pattern3)
command3
;;
esac

6.跳出循环 break & continue

continue例子如下：

参考：https://www.runoob.com/linux/linux-shell-process-control.html