re = /!(?!(.|\n|\r)*FastEthernet\d\d?\/\d\d?\.\d{1,3})/
str = 'interface FastEthernet0/0
shutdown
!
interface FastEthernet0/0.100
ip address 192.168.1.100
!
interface FastEthernet0/1
shutdown
!'
# Print the match result
str.match(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