Find CRLF in Notepad++

Solution 1:

[\r\n]+ should work too

Update March, 26th 2012, release date of Notepad++ 6.0:

OMG, it actually does work now!!!

Original answer 2008 (Notepad++ 4.x) - 2009-2010-2011 (Notepad++ 5.x)

Actually no, it does not seem to work with regexp...

But if you have Notepad++ 5.x, you can use the 'extended' search mode and look for \r\n. That does find all your CRLF.

(I realize this is the same answer than the others, but again, 'extended mode' is only available with Notepad++ 4.9, 5.x and more)

Since April 2009, you have a wiki article on the Notepad++ site on this topic:
"How To Replace Line Ends, thus changing the line layout".
(mentioned by georgiecasey in his/her answer below)

Some relevant extracts includes the following search processes:

Simple search (Ctrl+F), Search Mode = Normal

You can select an EOL in the editing window.

• Just move the cursor to the end of the line, and type Shift+Right Arrow.
• or, to select EOL with the mouse, start just at the line end and drag to the start of the next line; dragging to the right of the EOL won't work. You can manually copy the EOL and paste it into the field for Unix files (LF-only).

Simple search (Ctrl+F), Search Mode = Extended

The "Extended" option shows \n and \r as characters that could be matched.
As with the Normal search mode, Notepad++ is looking for the exact character.
Searching for \r in a UNIX-format file will not find anything, but searching for \n will. Similarly, a Macintosh-format file will contain \r but not \n.

Simple search (Ctrl+F), Search Mode = Regular expression

Regular expressions use the characters ^ and $ to anchor the match string to the beginning or end of the line. For instance, searching for return;$ will find occurrences of "return;" that occur with no subsequent text on that same line. The anchor characters work identically in all file formats.
The '.' dot metacharacter does not match line endings.

[Tested in Notepad++ 5.8.5]: a regular expression search with an explicit \r or \n does not work (contrary to the Scintilla documentation).
Neither does a search on an explicit (pasted) LF, or on the (invisible) EOL characters placed in the field when an EOL is selected. Advanced search (Ctrl+R) without regexp

Ctrl+M will insert something that matches newlines. They will be replaced by the replace string.
I recommend this method as the most reliable, unless you really need to use regex.
As an example, to remove every second newline in a double spaced file, enter Ctrl+M twice in the search string box, and once in the replace string box.

Advanced search (Ctrl+R) with Regexp.

Neither Ctrl+M, $ nor \r\n are matched.

The same wiki also mentions the Hex editor alternative:

• Type the new string at the beginning of the document.
• Then select to view the document in Hex mode.
• Select one of the new lines and hit Ctrl+H.
• While you have the Replace dialog box up, select on the background the new replacement string and Ctrl+C copy it to paste it in the Replace with text input.
• Then Replace or Replace All as you wish.

Note: the character selected for new line usually appears as 0a.
It may have a different value if the file is in Windows Format. In that case you can always go to Edit -> EOL Conversion -> Convert to Unix Format, and after the replacement switch it back and Edit -> EOL Conversion -> Convert to Windows Format.

Solution 2:

It appears that this is a FAQ, and the resolution offered is:

Simple search (Ctrl+H) without regexp

You can turn on View/Show End of Line or view/Show All, and select the now visible newline characters. Then when you start the command some characters matching the newline character will be pasted into the search field. Matches will be replaced by the replace string, unlike in regex mode.

Note 1: If you select them with the mouse, start just before them and drag to the start of the next line. Dragging to the end of the line won't work.

Note 2: You can't copy and paste them into the field yourself.

Advanced search (Ctrl+R) without regexp

Ctrl+M will insert something that matches newlines. They will be replaced by the replace string.