ref: a2a41a8e359dca5295c43dc2c2408094b96c3e0c dir: /testdir/t.aeiouy/
/^[^aeiouy]*a[^aeiouy]*e[^aeiouy]*i[^aeiouy]*o[^aeiouy]*u[^aeiouy]*y[^aeiouy]*$/