regex - 除非遇到两个连续的新行，否则如何为每两行插入一个新行？

Question

我试图为每两行文本插入一个新行，除非我想在遇到新段落(两个连续的新行)时重新启动此模式。 (我想要的输出不应该有三个连续的新行。)

例如，这是我的输入文本:

This is my first
line to appear in
the text.

I need the second
line to appear in
the way that follows
the pattern specified.

I am not sure if
the third line will
appear as I want it
to appear because sometimes
the new line happens where
there are two consecutive 
new lines.

这是我想要的输出:

This is my first
line to appear in

the text.

I need the second
line to appear in

the way that follows
the pattern specified.

I am not sure if
the third line will

appear as I want it
to appear because sometimes

the new line happens where
there are two consecutive

new lines.

我曾尝试使用 awk:

    awk -v n=2 '1; NR % n == 0 {print ""}'

但此命令不会在新段落后重新启动模式。相反，我会从上面的示例文本中得到以下输出:

This is my first
line to appear in

the text.


I need the second

line to appear in
the way that follows

the pattern specified.


I am not sure if
the third line will

appear as I want it
to appear because sometimes

the new line happens where
there are two consecutive

new lines.

正如这个不需要的输出所示，如果不重新启动模式，我将获得三个连续新行的实例。

Answer 1

perl 中的段落模式可以帮助:

perl -00 -ple 's/.*\n.*\n/$&\n/g'

输出

This is my first
line to appear in

the text.

I need the second
line to appear in

the way that follows
the pattern specified.

I am not sure if
the third line will

appear as I want it
to appear because sometimes

the new line happens where
there are two consecutive 

new lines.

基于@Borodin 评论:

perl -00 -ple 's/(?:.*\n){2}\K/\n/g'