Update:Enlil++ points out that the original solution below isn't. I completely missed capturing the first unquoted word in the example string, which translates to missing any and all unquoted strings that are not followed by a quoted string or the end-of-string! Whoops.

The addition of * at the end of the second regex fixes the problem (I think?).

$s = 'one seven eight two "three" four "five" "nine" ten eleven six tw
+elve';
@q = $S =~ m[" ( [^"]+  ) "]gx;
print @q
three five nine
@u = $S =~ m[(\S+)\s* (?: (?: " [^"]+ " \s*) | $ )* ]gx;
print @u
one seven eight two four ten eleven six twelve
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Provided your quoted strings don't contain embedded quotes, this should work once you've checked for balanced quotes. $string = 'one two "three" four "five" six'; @quoted = $string =~ m[" ( ^"+ ) "]gx; @unquoted = $string =~ m[(\S+)\s* (?: (?: " ^"+ " \s*) | $ )]gx; print @quoted; print @unquoted; three five two four six