bash 数组
有2种数组：
- 索引数组
- 关联数组（java里的Hashmap），用key关联value
声明数组：
#声明索引数组
declare -a ary
#声明关联数组
declare -a ary
引用数组：$
必须加大括号
直接访问数组名，就是访问第一个元素
[root@localhost ~]# ani[0]=dog
[root@localhost ~]# ani[1]=cat
[root@localhost ~]# echo ani
ani
[root@localhost ~]# echo ani[0]
ani[0]
[root@localhost ~]# echo $ani[0]
dog[0]
[root@localhost ~]# echo ${ani[0]}
dog
[root@localhost ~]# echo ${ani[1]}
cat
给数组赋值
-
单个赋值：ary[idx]=val
-
多个赋值：ary=(val1 val2...)
[root@localhost ~]# ary=(1 2 3 4 ) [root@localhost ~]# echo $ary 1 [root@localhost ~]# echo ${ary[0]} 1 [root@localhost ~]# echo ${ary[2]} 3 [root@localhost ~]# echo ${ary[1]} 2 [root@localhost ~]# echo ${ary[3]} 4 [root@localhost ~]# echo ${ary[4]} [root@localhost ~]# -
跳跃赋值：ary=([0]="aa" [3]="dd")
[root@localhost ~]# ary=([0]="aa" [3]="dd") [root@localhost ~]# echo ${ary[0]} aa [root@localhost ~]# echo ${ary[1]} [root@localhost ~]# echo ${ary[3]} dd
read读取数组
就选项-a就是读取数组
# read -a li
a b 1 d a2
[root@localhost ~]# echo $li
a
[root@localhost ~]# echo ${li[0]}
a
[root@localhost ~]# echo ${li[2]}
1
[root@localhost ~]# echo ${li[4]}
a2
取得数组元素的个数
- $
- $
取得数组中某个元素的长度
${#ary[indx/名字]}
得到数组的所以元素
- $
- $
关联数组
关联数组使用前最好先声明，使用-A选项声明。
[root@localhost scripts]# declare -A map
[root@localhost scripts]# map=([aa]=df12 [dd]=132432 [2]=12d)
[root@localhost scripts]# echo ${map[*]}
132432 df12 12d
[root@localhost scripts]# echo ${map[aa]}
df12
[root@localhost scripts]# echo ${map[2]}
12d
[root@localhost ~]# declare -A l3
[root@localhost ~]# l3[a]=aa
[root@localhost ~]# l3[b]=bb
[root@localhost ~]# echo ${l3[a]}
aa
[root@localhost ~]# echo ${l3[b]}
bb
[root@localhost ~]# echo ${#l3[*]}
2
[root@localhost ~]# echo ${#l3[@]}
2
[root@localhost ~]# echo ${#l3[a]}
2
[root@localhost ~]# echo ${#l3[b]}
2
[root@localhost ~]# l3[c]=1dsfs
[root@localhost ~]# echo ${#l3[c]}
5
[root@localhost ~]# echo ${l3[*]}
aa bb 1dsfs
[root@localhost ~]# echo ${l3[@]}
aa bb 1dsfs
数组的切片
${ary[@]:offset:length}
- offset：从第几个开始切
- length：切多长
[root@localhost scripts]# l1=(1 2 3 4 5 6)
[root@localhost scripts]# echo ${l1[@]:2:2}
3 4
删除数组里某个元素
# l1=(1 2 3 4 5 6)
[root@localhost scripts]# echo ${l1[@]:2:2}
3 4
[root@localhost scripts]# unset l1[1]
[root@localhost scripts]# echo ${l1[@]}
1 3 4 5 6
练习
1，生成10个随机整数，求最大值
$RANDOM是内置变量，能生成随机整数。
#!/bin/bash
#
declare -a rand
declare -i max=0
for i in {0..9}; do
rand[$i]=$RANDOM
echo ${rand[$i]}
if [ $max -lt ${rand[$i]} ]; then
max=${rand[$i]}
fi
done
echo "max is $max"
2，统计/var/log/*.log文件的行数之和。
关键点：files=(/var/log/*.log)。括号里是globbing风格，会自动展开。
#!/bin/bash
#
declare -a files
declare -i lines
files=(/var/log/*.log)
for ((i=0;i<${#files[*]};i++)); do
let lines+=`wc -l ${files[$i]} | cut -d" " -f1`
done
echo $lines
