re = /(?mi)^((?![0-9]+-[0-9]+).*?)(\bingenieur\b.*)/m
str = 'etudiant -: ingenieur etudes et developpement
http://www.doyoubuzz.com/profilen
experiences
ingenieur
2018-2014 ingenieur
331 ingenieur
29 rue de la terrasse Ingenieur Centrale Lyon / Supélec
93160 NOISY LE GRAND ingenieur
09 66 11 10 93 Expertise en instrumentation industrielle,
06 44 25 90 09 automatisation ingenieur & marketing opérationnel
email.email@wanadoo.fr Bilingue anglais ingenieur'
subst = '$1<i>$2</i>'
result = str.gsub(re, subst)
# Print the result of the substitution
puts result
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