Transpose File



Given a text file file.txt, transpose its content.

You may assume that each row has the same number of columns and each field is separated by the ' ' character.

For example, if file.txt has the following content:

name age
alice 21
ryan 30

Output the following:

name alice ryan
age 21 30

题意：从file.txt中读取数据，相当于调换行和列，将列变成行

思路：主要用了read -a来读取数据到数组中，以及涉及到数组的操作，如${#array_name[@]}表示数组array_name的长度，数组元素的引用${array_name[i]}表示数组array_name的第i个元素（下标从0开始）

代码如下：

while read -a columns #读取一行到数组columns中
do 
	for ((i=0; i < ${#columns[@]}; i++)) #  ${#columns[@]}表示数组长度
	do
		a[i]="${a[i]} ${columns[i]}"
	done
done < file.txt

for ((i=0; i < ${#a[@]};i++))
do
	echo ${a[i]}
done