Possibly a simplistic solution, but have you tried using negative lookahead? For instance: 
abowley@krait:~$ (echo 'Madrid(Spain' && echo 'Madrid(Spain)') | perl 
+-pe 's/\((?![^)]*\))/ /g;'
Madrid Spain
Madrid(Spain)

[download]
Breaking the regex down: 
s/
  \(      # an open bracket
  (?!     # _not_ followed by
    [^)]* # anything except brackets (e.g. 'Spain')
    \)    # followed by a bracket
  )
 / /gz;

[download]

In reply to Re: How do I replace certain character if condition exists by kilinrax
in thread How do I replace certain character if condition exists by peppiv

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