# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/(\(\d+), '(?!upload)(.*?)(?:[|]{3}.*?)?', (\d+\),?)/$1, 'upload\/$2', $3/gm;t' <<< "(37, '2011-01/1295144032_x_7cb0bcf1.jpg|||2011-01/1295266037_small_carterthal1.jpg.jpg|||2014-05/1401429739_3-fundamenta-vidyatshih2.jpg', 66),
(38, '2011-01/1295266433_event-image-poster.jpg|||2011-01/1295279508_16f7cb40.jpg', 67),
(39, '2012-01/1295277340_1.jpg|||2011-01/1295278172_08a9e04f4264-300x298.jpg|||2014-05/1401428634_vladislav-erko-castaneda-9.jpg', 68),
(68, '2011-03/1300177205_usui.jpg', 393),
(37, 'upload/2011-01/1295144032_x_7cb0bcf1.jpg', 66),
(38, 'upload/2011-01/1295266433_event-image-poster.jpg', 67),
(39, 'upload/2012-01/1295277340_1.jpg', 68),"
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 SED, please visit: https://www.gnu.org/software/sed/manual/html_node/The-_0022s_0022-Command.html