Perl在"-0"模式下匹配换行符 [英] Perl match newline in `-0` mode

问题描述

假设我有一个像这样的文件:

Suppose I have a file like this:

I've got a loverly bunch of coconut trees.

Newlines!

Bahahaha
Newlines!
the end.

我想替换出现的换行符"！用(例如)NEWLINES！包围着空白行.因此，理想的输出是:

I'd like to replace an occurence of "Newlines!" that is surrounded by blank lines with (say) NEWLINES!. So, ideal output is:

I've got a loverly bunch of coconut trees.

NEWLINES!

Bahahaha
Newlines!
the end.

尝试

忽略用换行符包围"，我可以这样做:

Attempts

Ignoring "surrounded by newlines", I can do:

perl -p -e 's@Newlines!@NEWLINES!@g' input.txt

替换所有出现的换行符！"并带有"NEWLINES！".

Which replaces all occurences of "Newlines!" with "NEWLINES!".

现在，我尝试仅选择换行符"！被\ n包围:

Now I try to pick out only the "Newlines!" surrounded with \n:

perl -p -e 's@\nNewlines!\n@\nNEWLINES!\n@g' input.txt

没有运气(请注意-我不需要s开关，因为我没有使用.，并且我不需要m开关，因为我没有使用^和;无论如何，添加它们都无法完成此工作).先行/后退也不起作用:

No luck (note - I don't need the s switch because I'm not using . and I don't need the m switch because I'm not using ^and $; regardless, adding them doesn't make this work). Lookaheads/behinds don't work either:

perl -p -e 's@(?<=\n)Newlines!(?=\n)@NEWLINES!@g' input.txt

经过一些搜索，我发现perl逐行读取文件(很有意义； sed也是).因此，我使用-0开关:

After a bit of searching, I see that perl reads in the file line-by-line (makes sense; sed does too). So, I use the -0 switch:

perl -0p -e 's@(?<=\n)Newlines!(?=\n)@NEWLINES!@g' input.txt

当然这是行不通的--0用空字符替换换行字符.

Of course this doesn't work -- -0 replaces new line characters with the null character.

所以我的问题是-我该如何匹配该模式(我不希望在regex的"s @ pattern @ replacement @ flags"结构之外编写任何Perl)?

So my question is -- how can I match this pattern (I'd prefer not to write any perl beyond the regex 's@pattern@replacement@flags' construct)?

是否可以匹配此空字符?我确实尝试过:

Is it possible to match this null character? I did try:

perl -0p -e 's@(?<=\0)Newlines!(?=\0)@NEWLINES!@g' input.txt

无效.

谁能告诉我如何在perl中匹配换行符?是否处于-0模式?还是应该使用awk之类的东西? (我从sed开始，但是即使使用-r，它似乎也没有超前/落后的支持.之所以选择perl是因为我对awk一点都不熟悉.)

Can anyone tell me how to match newlines in perl? Whether in -0 mode or not? Or should I use something like awk? (I started with sed but it doesn't seem to have lookahead/behind support even with -r. I went to perl because I'm not at all familiar with awk).

欢呼.

(PS:此问题不是我想要的，因为他们的问题与.+匹配的换行符有关.

(PS: this question is not what I'm after because their problem had to do with a .+ matching newline).

推荐答案

以下内容应该对您有用:

Following should work for you:

perl -0pe 's@(?<=\n\n)Newlines!(?=\n\n)@NEWLINES!@g'

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