To avoid Perl doing work when it doesn't have to, I prefer to write that as: 
$str =~ s/\s{2,}/ /g;

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Note also that using \s matches more than the space the OP mentioned. In particular, s/\s+/ /g or s/\s{2,}/ /g will replace one (two) or more newlines with a space.

In reply to Re^2: Replace consecutive whitespaces with single whitespace by JavaFan
in thread Replace consecutive whitespaces with single whitespace by Anonymous Monk

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