Shell脚本编程学习——Shell数组基础【显哥出品，必为精品】

一、Shell的数组概述

1.什么是数组

数组也是变量的一种

传统的变量只能存储一个值，但是数组可以存储多个值。

2.数组的分类

普通数组和关联数组 索引

普通数组：只能使用正整数作为数组索引

关联数组：不管可以使用整数作为索引，同时也可以使用字符串作为索引

二、普通数组的使用

1.单个赋值

[root@xian /server/scripts]# array[0]=lixian
[root@xian /server/scripts]# array[1]=18
[root@xian /server/scripts]# array[2]=boy
[root@xian /server/scripts]# echo ${array[*]}
lixian 18 boy
[root@xian /server/scripts]# declare -a |tail -1
declare -a array='([0]="lixian" [1]="18" [2]="boy")'

2. 赋值多个值

[root@xian /server/scripts]# array2=(lixian 18 'hen shuai')
[root@xian /server/scripts]# echo ${array2[*]}
lixian 18 hen shuai
[root@xian /server/scripts]# declare -a |tail -2
declare -a array='([0]="lixian" [1]="18" [2]="boy")'
declare -a array2='([0]="lixian" [1]="18" [2]="hen shuai")'

3.获取某个索引值的长度

[root@xian /server/scripts]# echo ${array[*]}
lixian 18 boy
[root@xian /server/scripts]# echo ${#array[0]}
6
[root@xian /server/scripts]# echo ${#array[1]}
2
[root@xian /server/scripts]# echo ${#array[2]}
3

4.获取数组中元数的个数（值的个数 或 索引的个数）

[root@xian /server/scripts]# echo ${array[*]}
lixian 18 boy
[root@xian /server/scripts]# echo ${#array[*]}
3
[root@xian /server/scripts]# echo ${#array[@]}
3

5.自定义索引及显示索引

[root@xian /server/scripts]# array2=(aaa bbb [6]=ccc ddd)
[root@xian /server/scripts]# echo ${!array2[*]}
0 1 6 7
[root@xian /server/scripts]# echo ${array2[*]:0}
aaa bbb ccc ddd
[root@xian /server/scripts]# echo ${array2[*]:1}
bbb ccc ddd
[root@xian /server/scripts]# echo ${array2[*]:2}
ccc ddd
[root@xian /server/scripts]# echo ${array2[*]:1:2}
bbb ccc
[root@xian /server/scripts]# echo ${array2[*]:1:3}
bbb ccc ddd

三、 关联数组的应用

1.单个赋值

[root@xian /server/scripts]# declare -A g_array
[root@xian /server/scripts]# g_array[name]=lixian
[root@xian /server/scripts]# g_array[age]=18
[root@xian /server/scripts]# g_array[skill]=linux
[root@xian /server/scripts]# g_array[like]=girl
[root@xian /server/scripts]# 
[root@xian /server/scripts]# echo ${g_array[*]}
girl lixian 18 linux

2.多个赋值

[root@xian /server/scripts]# declare -A g_array2
[root@xian /server/scripts]# g_array2=([name]=xiaoxian [age]=20 [skill]=linux [like]=boy)
[root@xian /server/scripts]# echo ${g_array2[*]}
boy xiaoxian 20 linux

3.显示关联数组及取消单个索引值

[root@xian /server/scripts]# declare -A | tail -2
declare -A g_array='([like]="girl" [name]="lixian" [age]="18" [skill]="linux" )'
declare -A g_array2='([like]="boy" [name]="xiaoxian" [age]="20" [skill]="linux" )'
[root@xian /server/scripts]# unset g_array2[skill]
[root@xian /server/scripts]# declare -A | tail -2
declare -A g_array='([like]="girl" [name]="lixian" [age]="18" [skill]="linux" )'
declare -A g_array2='([like]="boy" [name]="xiaoxian" [age]="20" )'

四、 数组遍历与循环

案例：根据passwd文件，取出每一种shell的数量

[root@xian /server/scripts]# cat passwd.sh 
#!/bin/bash
# File Name: passwd.sh
# Author: lixian
#######################
#声明关联数组
declare -A  Array_Shells
#批量赋值
while read line
do
    #Type=$(echo $line | awk -F: '{print $NF}')
    let Array_Shells[${line##*:}]++
done < /etc/passwd
#批量打印结果
for i in ${!Array_Shells[*]} 
do
    echo -e "Shell: $i\t\tCount: ${Array_Shells[$i]}"
done
[root@xian /server/scripts]# sh passwd.sh 
Shell: /sbin/nologin		Count: 21
Shell: /bin/sync		Count: 1
Shell: /bin/bash		Count: 7
Shell: /sbin/shutdown		Count: 1
Shell: /sbin/halt		Count: 1