# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/((?:\\/[A-Za-z0-9-]+)+)?(\\/tag\\/[A-Za-z0-9-%]+)+(\\/.*)?/$2/g;t' <<< "http://example.com/cat1/subcat3/subcat4/tag/this%20is%20page/asdasda?start=130/asdasdasd
http://example.com/cat1/subcat3/subcat4/tag/this%20is%20pageasdasd
example.it/news/tag/this%is%20n%page?adsadsadasd
http://example.com/tag/thispage/asdasdasd.-?asds=
http://example.com/tag/this%20is%20page/asdasd
http://example.com/tag/this
"
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