# Regex to Match Lines That Do Not Contain a Word

> Match lines that do not contain a word using a negative lookahead assertion in a PCRE regular expression, with global and multiline flags explained

**URL:** https://sentry.io/answers/write-a-regular-expression-to-match-lines-not-containing-a-word/

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## The Problem

How can I write a regular expression to match lines not containing a specific word?

## The Solution

You can do this using a [negative lookahead assertion](https://www.regular-expressions.info/lookaround.html). The [PCRE](https://www.pcre.org/) regular expression below will match any line that does not contain the word "word":

```
/^((?!word).)*$/gm
```

Here's what it does:

* `/`: Start regular expression.
* `^`: Match the beginning of a line.
* `(`: Start [capture group](https://www.regular-expressions.info/brackets.html) 1.
* `(?!word)`: Negative lookahead assertion. If "word" is found, discard the current match, otherwise continue evaluating the expression.
* `.`: Match any character.
* `)`: End capture group 1.
* `*`: Match 0 or more of capture group 1.
* `$`: Match the end of the line.
* `/`: End regular expression
* `g`: Global flag. Find all matches in the string, not just the first one.
* `m`: Multiline flag. Use `^` and `$` to match the start and end of a line, rather than the start and end of the whole string.

Notably, this expression will not match empty lines. If this behavior is desired, we can add the `s` (dotall) flag, which will make `.` match all characters including newlines:

```
/^((?!word).)*$/gms
```

If the `s` flag is not supported by your regex implementation, you can replace `.` with `[\s\S]` (`\s` matches whitespace characters, and `\S` matches everything except whitespace characters).

```
/^((?!word)[\s\S])*$/gm
```

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*Source: [sentry.io/answers/write-a-regular-expression-to-match-lines-not-containing-a-word/](https://sentry.io/answers/write-a-regular-expression-to-match-lines-not-containing-a-word/)*