re = /^[a-zA-Z0-9](?:[a-zA-Z0-9 ._-]*[a-zA-Z0-9])?\.[a-zA-Z0-9_-]+$/m
str = '## BELOW SHOULD MATCH
web.config
httpd.conf
test.txt
1.1
my long file name.txt
## BELOW SHOULD NOT MATCH
æøå.txt
hosts
.gitignore
.htaccess
test.t xt'
# 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