# Pattern to match optional lines in multiline messages

**URL:** <https://discuss.elastic.co/t/pattern-to-match-optional-lines-in-multiline-messages/71772>\
**Category:** Logstash\
**Created:** [January 16, 2017, 6:24pm UTC](https://discuss.elastic.co/t/pattern-to-match-optional-lines-in-multiline-messages/71772 "2017-01-16T18:24:35Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![eik3](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/eik3/32/12736_2.png) [@eik3](https://discuss.elastic.co/u/eik3)\
**Post date:** [January 16, 2017, 6:24pm UTC](https://discuss.elastic.co/t/pattern-to-match-optional-lines-in-multiline-messages/71772/1 "2017-01-16T18:24:35Z")

</div>

Here's the pattern

```auto
a:%{NOTSPACE:a}
(b:%{NOTSPACE:b})?
c:%{NOTSPACE:c}

```

This matches

```auto
a:1

c:42

```

and

```auto
a:1
b:23
c:42

```

But not

```auto
a:1
c:42

```

How can I make the pattern match the message even it the line `b` is completely missing?

---

<div class="post-metadata">

**Author:** ![eik3](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/eik3/32/12736_2.png) [@eik3](https://discuss.elastic.co/u/eik3)\
**Post date:** [January 16, 2017, 6:32pm UTC](https://discuss.elastic.co/t/pattern-to-match-optional-lines-in-multiline-messages/71772/2 "2017-01-16T18:32:14Z")

</div>

Got it: The pattern has to be a single line:  
`a:%{NOTSPACE:a}\n(b:%{NOTSPACE:b}\n)?c:%{NOTSPACE:c}`

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [February 13, 2017, 6:32pm UTC](https://discuss.elastic.co/t/pattern-to-match-optional-lines-in-multiline-messages/71772/3 "2017-02-13T18:32:29Z")

</div>

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