Bash和IFS:字符串拆分为具有特定分隔符的数组,并添加一个额外的空元素

关于将字符串拆分为数组,我们有两种情况:

如果字符串中有空格,如何使用分隔符,请按照以下帖子:

• Reading a space-delimited string into an array in Bash

因此,如果我使用:

string="Hello Unix World"
array1=($string)
echo ${array1[@]}
echo "size: '${#array1[@]}'"

read -a array2 <<< $string
echo ${array2[@]}
echo "size: '${#array2[@]}'"

Hello Unix World
size: '3'
Hello Unix World
size: '3'

这两种方法都能如期工作。

现在,如果字符串中有不同于空格的内容,如何使用分隔符,请参见以下帖子:

• How to split a string into an array in Bash?

因此,如果我使用:

path="/home/human/scripts"
IFS='/' read -r -a array <<< "$path"

echo "Approach 1"
echo ${array[@]}
echo "size: '${#array[@]}'"

echo "Approach 2"
for i in "${array[@]}"; do
   echo "$i"
done

echo "Approach 3"
for (( i=0; i < ${#array[@]}; ++i )); do
    echo "$i: ${array[$i]}"
done

Approach 1
home human scripts    <--- apparently all is ok, but see the line just below!
size: '4'
Approach 2
                      <--- an empty element
home
human
scripts
Approach 3
0:                    <--- confirmed, the empty element
1: home
2: human
3: scripts

为什么会出现空元素?如何修复命令以避免这种情况?