1.shell实现斐波那契数列

##实现一
arr[0]=1
arr[1]=1
i=0
read max

while [ $i -le $max ]
do
    let arr[$i+2]=arr[$i+1]+arr[$i]
    let i++
done

echo ${arr[$max]}


#实现二
function fib()
{
    temp=$1
    if [ $temp -lt 2 ] ;then
        echo 1
        return 
    fi

    res1=`fib $((temp-1))`
    res2=`fib $((temp-2))`

    echo $((res1+res2))
}


#read num
#fib $num

#实现三
first=1
second=1
last=1

if [ $1 -lt 2 ];then

    echo 1
fi

i=2
while [ $i -le $1 ]
do
    let last=$first+$second
    let first=$second
    let second=$last
    let i++
done
echo $last

2.. ⽂文件内容如下：

123abc456
456def123
567abc789
789def567
要求输出：
456ABC123
123DEF456
789ABC567
567DEF789

实现思路：按行读取，将一行切割成三部分，
第二部分字母转化为小写转化为大写
最后拼接成一块输出@R_301_458@到另一个文件

while read line
do
    part1=$( echo $line |cut -c 1-3 )
    part2=$( echo $line |cut -c 4-6 |tr '[a-z]' 'A-Z')
    part3=$( echo $line |cut -c 7-9 )
    echo ${part3}${part2}${part1}
done < file1 >file2

3.用Shell实现希尔排序

function shell_sort()
{
    echo ${a[*]}
    size=${#a[@]}
    gap=$size
    #for (( gap=size/3+1;$gap>1; gap=$gap/3+1 ))
    while((gap>1))
    do
        let gap=$gap/3+1
        for ((idx=gap;idx<size;idx++))
        do
            let pre=idx-gap
            let save=${a[idx]}
            #while [ $pre -ge 0 && $save -le ${a[$pre]} ]
            while ((pre>=0&&a[pre]>save))
            do
                let a[pre+gap]=a[pre]
                let pre-=gap
            done
            let a[$pre+gap]=$save
            echo ${a[*]}
        done
    done
echo ${a[@]}
}

echo "please input num"

read num
i=0
while [ $num -gt 0 ]
do
    read a[i]
    let i++
    let num-=1
echo ${a[*]}
done


shell_sort $@