shell脚本字符串和数组的使用操作方法

#! /bin/bash
username="mayuan"
str_1="hello ${username}" 
str_2='hello ${username}'
echo $str_1 # hello mayuan
echo $str_2 # hello ${username}

#! /bin/bash
username="mayuan"
echo ${#username} # 6

#! /bin/bash
username="mayuan"
echo ${username:1:3} # 从第二个字符开始截取3个字符输出"ayu"

#! /bin/bash
username="mayuan"
echo $(expr index "${username}" y) #查找y在指定字符的位置

#! /bin/bash
arr=(1 2 3 4 5)
echo ${arr[0]} #输出1
echo ${arr[1]} #输出2

#! /bin/bash
arr=(1 2 3 4 5)
echo ${#arr[@]} #输出5
echo ${#arr[*]}

#!/bin/bash
a="hello,world,nice,to,meet,you"
#要将$a分割开，先存储旧的分隔符
OLD_IFS="$IFS"
#设置分隔符
IFS="," 
#如下会自动分隔
arr=($a)
#恢复原来的分隔符
IFS="$OLD_IFS"
#遍历数组
for s in ${arr[@]}
do
echo "$s"
done