Regexp in Grok sometimes catches a value sometimes not
问题 I've a code in grok, which captures messages, and if they meet a given criteria, they get a tag. My problem is, that sometimes this filter works while testing, and sometimes does not. The regexp in question is the following: ^(?!(?:\d\d\d\d-\d\d-\d\d.\d\d:\d\d:\d\d)).*$ This line checks if the given message does not begin with a given time stamp format. In other words: if the given message does not begin with this time stamp, then it gets a tag. You can test it yourself with this online