linux while循环

while循环的格式

while expression
do
command
command
```
done

一、计数器控制的while循环

#!/bin/sh
int=1
while(( $int<=5 ))
do
echo $int
let "int++"
done

二、结束标记控制的while循环

 #用脚本演示使用结束标记控制while循环实现猜1～10内的数
 #!/bin/sh
 echo "Please input the num (1~~10): "
 read num
 while [[ $num != 4 ]]
 do
 if [ $num -lt 4 ]
 then
 echo "Too small ,Try again.."
 read num
 elif [ $num -gt 4 ]
 then
 echo "Too big ,Try again.. "
 read num
 else
 exit 0
 fi
 done
 echo "Yes ,you are right !!"

三、标致控制的while循环

 #!/bin/sh
 echo "Please input the num:"
 read num
 sum=0
 i=1
 signal=0
 while [[ $signal != 1 ]]
 do
 if [ $i -eq $num ]
 then
 let "signal=1"
 let "sum+=i"
 echo "1+二、、、+$num=$sum"
 else
 let "sum=sum+i"
 let "i++"
 fi
 done

四、命令行参数控制的while循环

 #!/bin/sh
 echo "Please input arguements is $# "
 echo "What you input : "
 while [[ $* != "" ]]
 do
 echo $1
 shift
 done