有2種數組：

• 索引數組
• 關聯數組（java里的Hashmap），用key關聯value

聲明數組：

#聲明索引數組
declare -a ary
#聲明關聯數組
declare -a ary

引用數組：${ary[idx]}

必須加大括弧

直接訪問數組名，就是訪問第一個元素

[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

給數組賦值

• 單個賦值：ary[idx]=val

• 多個賦值：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 ~]#

• 跳躍賦值：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讀取數組

就選項-a就是讀取數組

# 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

取得數組元素的個數

• ${#ary[*]}
• ${#ary[@]}

取得數組中某個元素的長度

${#ary[indx/名字]}

得到數組的所以元素

• ${ary[*]}
• ${ary[@]}

關聯數組

關聯數組使用前最好先聲明，使用-A選項聲明。

[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

數組的切片

${ary[@]:offset:length}

• offset：從第幾個開始切
• length：切多長

[root@localhost scripts]# l1=(1 2 3 4 5 6)
[root@localhost scripts]# echo ${l1[@]:2:2}
3 4

刪除數組裡某個元素

# 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

練習

1，生成10個隨機整數，求最大值

$RANDOM是內置變數，能生成隨機整數。

#!/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，統計/var/log/*.log文件的行數之和。

關鍵點：files=(/var/log/*.log)。括弧里是globbing風格，會自動展開。

#!/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