regex with negative matching (ie, find string that _doesn't_ match regex)

Question

I have a log file with the string "ERROR" on some lines. I want to delete every line that doesn't have ERROR so that I can see just what needs fixing. I was going to do something like the following in vim:

%s/!(ERROR)//

to replace non-error lines with an empty string.

I do not believe that standard regexes can do this, but maybe I'm wrong...

too much php · Accepted Answer · 2009-07-22 00:15:44Z

55

Use the :g! command to delete every line that doesn't match.

:g!/ERROR/d

answered Jul 22, 2009 at 0:15

too much php

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1 Comment

rampion Over a year ago

:v/ERROR/d is equivalent

Greg Hewgill · Accepted Answer · 2009-07-22 00:35:37Z

8

In vim, you can run any filter command on the text in the buffer. For example,

:%!grep ERROR

will replace the entire buffer with only the lines that match the given regular expression.

This is useful for more than just grep, for example you can sort the lines in the buffer with :%!sort. Or, you can do the same for any range of text using the V command to mark the block and then :!filter-command (vim will automatically fill in '<,'> for you to indicate the currently marked block).

answered Jul 22, 2009 at 0:35

Greg Hewgill

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2 Comments

too much php Over a year ago

+1 for a command that doesn't require leaving vim / redirecting into a different file

ephemient Over a year ago

Maybe not the best of examples, as :grep and :sort do have built-in meanings in Vim (which are different than :!grep and :!sort, just to be confusing).

ghostdog74 · Accepted Answer · 2009-07-22 00:32:29Z

1

if on *nix, you can use grep -v or awk

awk '!/ERROR/' file | more

on a windows machine, you can use findstr

findstr /v /c:ERROR file | more

answered Jul 22, 2009 at 0:32

ghostdog74

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Comments

Alexander Bird · Accepted Answer · 2010-04-05 18:26:51Z

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Using a negative lookahead worked.

answered Apr 5, 2010 at 18:26

Alexander Bird

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2 Comments

atomicules Over a year ago

Not a very useful answer without an example: :%s/^$\ERROR$\@!$\n//g. In Vim the \@! is the negative lookahead indicator, not the (?!) format from that link. The :g! answer is easier though.

Michael Scheper Over a year ago

I agree with @atomicules, but I'm nevertheless upvoting Alexander's answer because 'negative lookahead' is a useful term for further websearching.

Jaelebi · Accepted Answer · 2009-07-22 00:19:00Z

0

A negative matching regex will use ^ For eg. [^E] will match everything except E.

answered Jul 22, 2009 at 0:19

Jaelebi

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Greg Hewgill Over a year ago

That's true, but such a regex will match every character that's not E, which is different from matching all lines that do not contain E. Also, such a negative match is awkward to extend beyond one character.

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