re = /^\[([^\]]+)\] \[(오[전후] \d{1,2}:\d{2})\] (.*)$/m
str = '[철수] [오전 2:06] 메세지본문
위와 같은 문자열에서 사람이름, 시간, 메세지 본문을 따로 뽑아오고싶은데 정규표현식을 제대로 다뤄본적이 없어 고전중입니다 ㅠㅠ'
subst = '$3 - $2, $1'
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