Delete all lines (not) matching a regex using Notepad++

Question

How to delete all lines matching or not matching a regex in Notepad++?

In Vim, I'd do the following to delete all matching lines:

:g/regex/d

And to delete all non matching lines:

:!g/regex/d

I'm looking for these commands' equivalent in Notepad++.

As also explained in "Notepad++ - delete all lines with certain text", I usually go for the approach of blanking the matching lines and deleting the blank lines afterwards. Is there a simpler way?

As per this answer, versions of Notepad++ >= 6.0 support matching line breaks in regex, thus allowing to delete whole lines directly without creating blank lines first. The following pattern should remove all lines containing "foobar" when replaced with an empty string:

^.*foobar.*\r\n

Now, as discussed in "Regular expression to match a line that doesn't contain a word?", negating regular expressions isn't exactly straightforward. Deleting lines in Notepad++ which do not contain "foobar" would require the following pattern:

^((?!foobar).)*\r\n

Because that's a quite complicated command to type just for removing lines which don't contain a word (or possibly more complex expression), I wonder if there is an easier solution.

Are you interested in 1-step solution only? There is another solution, an unroll-the-loop one: ^[^f\n]*(?:f(?!oobar)[^f\n]*)*(?:\R|$), but again it might look "complicated". — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Dec 24, 2015 at 22:23
I'm interested in the solution which takes the fewest keystrokes/clicks. :) — tmh
– tmh, Commented Dec 24, 2015 at 22:25

qubodup · Accepted Answer · 2023-08-25 11:08:32Z

59

In the Find (Ctrl + F or Search > Find) dialog, on the Mark tab, you can Bookmark lines that match.

Then use the menu item Search > Bookmark > Remove Non-Bookmarked Lines or Remove Bookmarked lines.

edited Aug 25, 2023 at 11:08

qubodup

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answered Dec 24, 2015 at 22:25

Captain

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7 Comments

tmh Over a year ago

This is probably fastest way to do it in Notepad++. :)

Nicholas DiPiazza Over a year ago

yeah that's a great way to do it!

Umair Ayub Over a year ago

I have matched some part of each line so this doesnt work for me

Phil Over a year ago

for those finding this now, you need to check "Bookmark line" checkbox for this to work. @UmairAyub

GriffoGoes Over a year ago

If I could upvote twice I would! Super easy to do, but I always forget that the Remove Unmarked Lines is inside the Search menu

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