Why is \r a newline for Vim?

Question

From question How to replace a character for a newline in Vim?. You have to use \r when replacing text for a newline, like this

:%s/%/\r/g

But when replacing end of lines and newlines for a character, you can do it like:

:%s/\n/%/g

What section of the manual documents these behaviors, and what's the reasoning behind them?

@qed: by default `:s` will only apply the substitution to the current line. `:%s` makes it address the whole file. [More](http://vim.wikia.com/wiki/Search_and_replace). — c24w, Jan 06 '14 at 14:09
+c24w I think he is referring to the '%' between the slashes, the first example the '%' being in the search location, and in the replace location in the second example, but @qed to answer your question, those '%'s are matched literally. — RastaJedi, Aug 24 '16 at 02:57

score 239 · Answer 1 · answered Sep 12 '12 at 13:02

239

From http://vim.wikia.com/wiki/Search_and_replace :

When Searching

...

\n is newline, \r is CR (carriage return = Ctrl-M = ^M)

When Replacing

...

\r is newline, \n is a null byte (0x00).

answered Sep 12 '12 at 13:02

lmat - Reinstate Monica

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This answer helped me the most. Also, for more information, `:h :s%`, especially the last paragraph. (via `:h :s`) – dipnlik Oct 20 '14 at 12:56
i wrote about that in even more depth - https://stackoverflow.com/a/18961239/805284 – sjas Jul 31 '20 at 14:18
Yes, you wrote more, but I don't think you added anything material. – lmat - Reinstate Monica Aug 01 '20 at 15:13
but WHY........ – IceFire Jul 21 '23 at 15:06
@IceFire Excellent question. I have no idea (even 13 years later). It's just one more "grey-beard" thing we have to memorize to make ourselves into the GNU/Linux sages we revere. :sigh: – lmat - Reinstate Monica Jul 24 '23 at 03:46

score 157 · Accepted Answer · edited May 27 '15 at 19:25

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From vim docs on patterns:

\r matches <CR>

\n matches an end-of-line - When matching in a string instead of buffer text a literal newline character is matched.

edited May 27 '15 at 19:25

iconoclast

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answered Sep 16 '08 at 15:16

pjz

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For me the point of confusion is that \r and \n mean different things when used is the search pattern and the replacement pattern. – dlamblin Dec 04 '12 at 17:09
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@dlamblin Yup! See my answer :) – lmat - Reinstate Monica Jun 28 '14 at 01:54
The question in the title is "why" and this is not answered – IceFire Jul 21 '23 at 15:07

rking · Answer 3 · 2012-10-18T07:53:27.417

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Another aspect to this is that \0, which is traditionally NULL, is taken in s//\0/ to mean "the whole matched pattern". (Which, by the way, is redundant with, and longer than, &).

So you can't use \0 to mean NULL, so you use \n
So you can't use \n to mean \n, so you use \r.
So you can't use \r to mean \r, but I don't know who would want to add that char on purpose.

—☈

edited Oct 18 '12 at 07:53

answered Sep 12 '12 at 13:54

rking

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Good point! So this is a hack around \0 - backreference to 0-th nested group - whole regexp. This is a very good answer, but it makes me dissapointed, that I can't use \r in replacement... (meaning: insert #(13), for example in a "normal" file (== unix EOLs). – Tomasz Gandor Nov 06 '13 at 09:54
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OK, the answer is in the Vim docs. Just escape \^M or \, with a normal backslash. Nice. ----- split line in two at this point (Type the as CTRL-V ) *s* \r idem -------- *s/\r* \ insert a carriage-return (CTRL-M) (Type the as CTRL-V ) *s/\* – Tomasz Gandor Nov 06 '13 at 10:03
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"Another aspect"? You're too modest! Explaining precisely_why_ this happens makes for a superior answer to all the ones just saying _how_ to work around it. +1 – underscore_d Oct 20 '15 at 13:23
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This is honestly *really* great insight into why `\n` has different meanings in search and replace patterns. Fantastic answer. – ZeroKnight Apr 30 '19 at 10:51

score 50 · Answer 4 · edited Jul 03 '14 at 14:08

`:help NL-used-for-Nul`

Technical detail:

<Nul> characters in the file are stored as <NL> in memory. In the display they are shown as "^@". The translation is done when reading and writing files. To match a <Nul> with a search pattern you can just enter CTRL-@ or "CTRL-V 000". This is probably just what you expect. Internally the character is replaced with a <NL> in the search pattern. What is unusual is that typing CTRL-V CTRL-J also inserts a <NL>, thus also searches for a <Nul> in the file. {Vi cannot handle <Nul> characters in the file at all}

score 12 · Answer 5 · answered Dec 10 '13 at 10:28

First of all, open :h :s to see the section "4.2 Substitute" of documentation on "Change". Here's what the command accepts:

:[range]s[ubstitute]/{pattern}/{string}/[flags] [count]

Notice the description about pattern and string

For the {pattern} see |pattern|.
{string} can be a literal string, or something
special; see |sub-replace-special|.

So now you know that the search pattern and replacement patterns follow different rules. If you follow the link to |pattern|, it takes you to the section that explains the whole regexp patterns used in Vim.

Meanwhile, |sub-replace-special| takes you to the subsection of "4.2 Substitute", which contains the patterns for substitution, among which is \r for line break/split.

(The shortcut to this part of manual is :h :s%)

Why is \r a newline for Vim?

5 Answers5

`:help NL-used-for-Nul`

Technical detail:

Linked

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