记录 shell学习过程（4）for 循环

1. for in 

1 for i in `seq 1 10`   #seq 生成从1到10  如果生成从10到1则写作 seq 10 -1 1
2   do
3      echo $i
4 done

for in 也可以循环出字符串

for i in where is a will there is a way
   do
      echo "word:$i"
done

2.双小括号

1 for (( i=0;i<10;i++ )) #2个小括号是为了做运算
2   do
3       echo $i
4 done