shell基础——循环

语法：

for i in 1 2 3 4
do
    command
done


for ((var=1 ; var<6 ; var++))
do
    command
done


for ((var=5 ; var>0 ;var--))
do
    command
done


for i in $(seq 100)    #产生1到100的序列
do
    command
done


for i in $(seq 1 2 100)    #从1到100，步长2
for i in {50..100}
for i in {50..100..2}
for i in {100..50..-2}
for ((i=50 ;i<101 ; i+=2))
for i in $(ls)

while [条件]
do
    command
done

while true    #死循环

 

continue    ——重新开始循环
break    ——跳出循环
exit    ——直接跳出程序
　　exit　10　——退出程序并返回10