I need to extract numbers like 2.268 out of strings that contain the word output:

Approxmiate output size of output: 2.268 kilobytes

But ignore it in strings that don't:

some entirely different string: 2.268 kilobytes

This regex:

(?:output. ?)([\d\.] )

Gives me a match with 1 group, with the group being 2.268 for the target string. But since I'm not using a programming language but rather CloudWatch Log Insights, I need a way to only match the number itself without using groups.

I could use a positive lookbehind ?<= in order to not consume the string at all, but then I don't know how to throw away size of output: without using . , which positive lookbehind doesn't allow.

CodePudding user response：

Since you are using PCRE, you can use

output.*?\K\d[\d.]*

See the regex demo. This matches

• output - a fixed string
• .*? - any zero or more chars other than line break chars, as few as possible
• \K - match reset operator that removes all text matched so far from the overall match memory buffer
• \d - a digit
• [\d.]* - zero or more digits or periods.