# Special characters in regex pattern

**URL:** <https://discuss.elastic.co/t/special-characters-in-regex-pattern/213380>\
**Category:** Logstash\
**Created:** [December 30, 2019, 9:03pm UTC](https://discuss.elastic.co/t/special-characters-in-regex-pattern/213380 "2019-12-30T21:03:48Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Jeremy\_Andrews](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jeremy_andrews/32/60104_2.png) [@Jeremy\_Andrews](https://discuss.elastic.co/u/Jeremy_Andrews)\
**Post date:** [December 30, 2019, 9:03pm UTC](https://discuss.elastic.co/t/special-characters-in-regex-pattern/213380/1 "2019-12-30T21:03:48Z")

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I’m trying to write an if statement in Logstash to check if the message starts with a certain pattern, but Logstash crashes without any useful reason given in the log. I’m wondering if I’m not escaping the special character properly? Do you notice anything wrong with this line? I’m trying to drop any log which begins with \</System

`if [message] =~ /^<\/System/ { drop {} }`

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**Author:** ![Badger](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/badger/32/25190_2.png) [@Badger](https://discuss.elastic.co/u/Badger)\
**Post date:** [December 30, 2019, 9:40pm UTC](https://discuss.elastic.co/t/special-characters-in-regex-pattern/213380/2 "2019-12-30T21:40:00Z")

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> [@Jeremy\_Andrews](#):
>
> Logstash crashes without any useful reason given in the log

What does it log?

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [January 27, 2020, 9:40pm UTC](https://discuss.elastic.co/t/special-characters-in-regex-pattern/213380/3 "2020-01-27T21:40:01Z")

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