re = /^\[[^\]]*\]\[(?<type>[^\]]+)/m
str = '[2023-07-19T03:55:16,043][ERROR][o.o.s.i.DetectorIndexManagementService] [opensearch-cluster-master-2] info deleteOldIndices'
# Print the match result
str.scan(re) do |match|
puts match.to_s
end
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html