Ubuntu12.04 TLS 64bit, bash 4.2.25
一、定义
数组是一些数据的集合,分为两个类型
(1)普通数组,只能使用整数作为索引
(2)关联数组,可以使用字符串作为索引,bash 4.0开始支持,旧版版不支持
二、数组的一些操作
(1)数组的定义以及赋值
<普通数组>
【1】定义
数组名 = ()
【2】赋值
1. 数组名 = (elem1 elem2 elem3 ......)
每个元素由空格隔开
2. 数组名[0] = "test1"
数组名[1] = "test2"
......
<关联数组>
【1】定义
declare -A 数组名
【2】赋值
1. 数组名 = ([index1] = val1 [index2] = val2 .....)
2. 数组名[index1] = val1
数组名[index2] = val2
......
(2)求数组的长度
${#数组名[*]} 或 {#数组名[@]}
(3)获得数组制定索引的元素
${数组名[索引值]}
(4)获得数组的所有元素
${数组名[*]} 或 ${数组名[@]}
(5)数组元素的替换
${数组名[*]/查找字符/替换字符} 或 ${数组名[@]/查找字符/替换字符}
替换并没有改变原来的数组,要修改原来的数组,需要对数组重新赋值
(6)删除数组元素
unset 数组名 #删除整个数组 unset 数组名[索引值] #删除指定的元素
(7)数组的切片
${数组名[*]:起始位置:长度} 或 ${数组名[@]:起始位置:长度}
切片后返回的是由空格隔开的字符串,加上()后将得到切片后的子数组
(8)获得数组的所有索引值
${!数组名[*]} 或 ${!数组名[@]}
三、例子
#!/bin/bash #定义普通数组并进行赋值 comm_arr=(1 2 3 4 5) comm_arr2=() comm_arr2[0]=6 comm_arr2[1]=7 comm_arr2[2]=8 #获得普通数组的长度 echo "comm_arr1 len is ${#comm_arr[*]}" echo "comm_arr2 len is ${#comm_arr2[@]}" #获得普通数组的所有元素 echo "comm_arr1 all elem is : ${comm_arr[*]}" echo "comm_arr2 all elem is :${comm_arr2[@]}" #通过索引获得元素 echo "comm_arr[4] = ${comm_arr[4]}" echo "comm_arr[2] = ${comm_arr2[2]}" echo "comm_arr[100] = ${comm_arr[100]}" #索引值不存在,但不出错,结果为空 #普通数组中元素的替换 echo "3 in comm_arr is replace 200 : ${comm_arr[*]/3/200}" echo "comm_arr is ${comm_arr[*]}" #原数组没有被修改 comm_arr2=(${comm_arr2[@]/7/9}) #替换原数组 echo "7 in comm_arr2 is replace 9 and modify comm_arr2" echo "comm_arr2 is ${comm_arr2[*]}" #普通数组的切片 echo "splite comm_arr 1-3 is : ${comm_arr[*]:1:3}" comm_arr_split=(${comm_arr[@]:2:3}) #获得从第三个位置子开始3个元素的子数组 echo "sub arr : len = ${#comm_arr_split[*]} , elems is : ${comm_arr_split[@]}" #普通数组的删除 echo "del before, comm_arr is ${comm_arr[*]}" echo "del a elem" unset comm_arr[0] #删除某个元素 echo "del after, comm_arr is ${comm_arr[*]}" echo "del all arr" unset comm_arr #删除整个数组 echo "del after, comm_arr is ${comm_arr[*]}" #为空 #获得所有索引值 echo "indexs is ${!comm_arr2[@]}" #定义关联数组并赋值 declare -A link_arr link_arr['apple']='10$' link_arr[orange]='100Y' declare -A link_arr2 link_arr2=([age]=20 [name]=zhangsan [sex]=m) #获得关联数组的长度 echo "link arr len: ${#link_arr[*]}" echo "link arr2 len: ${#link_arr2[@]}" #通过索引获得元素 echo "link arr index=apple, elem is ${link_arr['apple']}" echo "link arr2 index=name, elem is ${link_arr2[name]}" echo "link arr index=name not exist, but no error, ${link_arr[name]}" #虽然没有这个索引,但不会错误,只是结果为空 #输出关联数组中所有元素 echo "apple is ${link_arr[*]}" echo "link_arr2 is ${link_arr2[@]}" #关联数组中的替换 echo "link arr2 zhangsan is replace lisi, ${link_arr2[*]/zhangsan/lisi}" #原数组没有修改 echo "link arr2 is ${link_arr2[*]}" #link_arr2=(${link_arr2[*]/zhangsan/lisi}) #报错,关联数组必须使用下标 #echo "link arr2 is ${link_arr2[*]}" #echo "link arr2 name=${link_arr2[name]}" #关联数组的切片 echo "link arr2 age-name: ${link_arr2[*]:name:2}" #关联数组的删除 echo "del before link arr2 is ${link_arr2[*]}" unset link_arr2[age] echo ""del after link arr2 is ${link_arr2[*]} unset link_arr echo "del all arr ${link_arr[*]}" #获得所有的索引值 echo "link arr2 indexs : ${link_arr2[*]}"
结果:
comm_arr1 len is 5
comm_arr2 len is 3
comm_arr1 all elem is : 1 2 3 4 5
comm_arr2 all elem is :6 7 8
comm_arr[4] = 5
comm_arr[2] = 8
comm_arr[100] =
3 in comm_arr is replace 200 : 1 2 200 4 5
comm_arr is 1 2 3 4 5
7 in comm_arr2 is replace 9 and modify comm_arr2
comm_arr2 is 6 9 8
splite comm_arr 1-3 is : 2 3 4
sub arr : len = 3 , elems is : 3 4 5
del before, comm_arr is 1 2 3 4 5
del a elem
del after, comm_arr is 2 3 4 5
del all arr
del after, comm_arr is
indexs is 0 1 2
link arr len: 2
link arr2 len: 3
link arr index=apple, elem is 10$
link arr2 index=name, elem is zhangsan
link arr index=name not exist, but no error,
apple is 100Y 10$
link_arr2 is zhangsan 20 m
link arr2 zhangsan is replace lisi, lisi 20 m
link arr2 is zhangsan 20 m
link arr2 age-name: zhangsan 20
del before link arr2 is zhangsan 20 m
del after link arr2 is zhangsan m
del all arr
link arr2 indexs : zhangsan m
四、总结
【1】与C语言的数组相比较
(1)C语言的数组的下标值只能是整数; 而shell的数组的下标值可以是字符串
(2)C语言的数组的内容是一组相同类型的元素; 而shell数组的内容可以是混杂的
(3)C语言的数组的大小在声明的时候就必须指定,并且大小不能扩增; 而shell数组声明不需要指定大小,直接添加元素即可
(4)访问C语言的数组时, 下标值不能越界, 否则出错; 而shell数组没有限制,访问不存在的下标的元素时返回空,而不出错
(5)C语言数组没有shell数组那么多操作