Hi, where can i find the rules of nifi's regex language ?

[#1]

Hi @Thierry Vernhet

NiFi is using Java regular expressions.

Personally, I am using http://regexr.com/ to check my regular expressions.

[#2]

+1 for the RegexR - i wrote some more complex expressions with it, it has a great interactive and visual explainer to help you out as you progress. The final expression can be copied as is from there into NiFi, no special escapes needed, etc.

[#3]

Does regexr.com validates if your Nifi expression is valid as well?

[#4]

Thanks. I'm a novice nifi's user.

I've got in a "extract text" processor this property "grok" below.

grok

^((?<year>\d+).*)$

And I don't understand exactly what it means and espacially "\d+" and ".*"

[#5]

Check out http://regexr.com/ CheatSheet and Examples menu item on the left.

[#6 · Accepted solution]

Java reference : https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html

\d stands for a digit [0-9] and + means at least one digit.

.* means any characters

[#7]

I find nifi regex to have less options. The same regex ( [\.]conf ) in my case to find a configuration file works from outside Nifi.

But on putting this pattern in Nifi ListHDFS processor , File Pattern will not match and the file is never pulled.

Any idea why this would happen ?

[#8]

Hi, personally I am using https://www.debuggex.com/ and https://extendsclass.com/regex-tester.html to check regex.