shell 脚本中所有循环语法

写出 shell 脚本中所有循环语法

for 循环 :

for i in $(ls);do
echo item:$i
done

while 循环 :

#!/bin/bash
COUNTER=0
while [ $COUNTER -lt 10 ]; do
echo The counter is $COUNTER
let COUNTER=COUNTER+1
done

until 循环 :

#!/bin/bash
COUNTER=20
until [ $COUNTER -lt 10 ]; do
echo COUNTER $COUNTER
let COUNTER-=1
done