shell命令之基本的数组操作

Arrays in bash

i=0
while read line
do
arr[$i]=$line
((i++))
done
echo ${arr[@]}       //echo ${arr[@]}输出所有的数组元素

**Input**
Namibia
Nauru
Nepal
Netherlands
NewZealand
Nicaragua
Niger
Nigeria
NorthKorea
Norway
**Output**
Namibia Nauru Nepal Netherlands NewZealand Nicaragua Niger Nigeria NorthKorea Norway

i=0
while read line
do
arr[$i]=$line
((i++))
done
echo ${arr[@]/*[aA]*/}

**Input**
Namibia
Nauru
Nepal
Netherlands
NewZealand
Nicaragua
Niger
Nigeria
NorthKorea
Norway
**Output**
Niger

**Output2**
echo ${arr[@]/*[aA]*/hello}  //使用hello替换掉所有包含a的文本行
hello hello hello hello hello hello Niger hello hello hello

X=$(paste -sd' ' fileName)
echo $X $X $X

X=$(cat fileName)
echo $X $X $X

**Output**
Namibia Nauru Nepal Netherlands NewZealand Nicaragua Niger Nigeria NorthKorea Norway Namibia Nauru Nepal Netherlands NewZealand Nicaragua Niger Nigeria NorthKorea Norway Namibia Nauru Nepal Netherlands NewZealand Nicaragua Niger Nigeria NorthKorea Norway

echo ${arr[3]}

a.使用wc命令
wc -l

b.使用echo命令
arr=($(cat))
echo ${#arr[@]}

c.使用for循环
i=0
while read line
do
arr[$i]=$line
((i++))
done
echo "$i"

a.使用sed命令仅替换第一个大写字母为.
sed 's/[A-Z]/./' | paste -sd ' '

b.使用数组的替换来实现
X=($(cat))
echo "${X[@]/[A-Z]/.}"

**Output**
.amibia .auru .epal .etherlands .ewZealand .icaragua .iger .igeria .orthKorea .orway

a.首先将' '替换为换行，然后对每行数据排序，获取只出现一次的数字
tr ' ' '\n' | sort | uniq -u