# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/(.*?)(\[\w{3}=\')(\w+\.\w+)(\'\])(.*?)(\[\w{3}=\')(\w+\.\w+).*/$1 <object data=\"https:\/\/myurl.com\/media\/$3\" class=\"pdf-shortcode-iframe" type=\"application\/pdf\"> <iframe class=\"pdf-shortcode-iframe\" src=\"https:\/\/docs.google.com\/viewer?url=https:\/\/myurl.com\/media\/$3&embedded=true\"><\/iframe> <\/object>$5 <object data=\"https:\/\/myurl.com\/media\/$7\" class=\"pdf-shortcode-iframe\" type=\"application\/pdf\"> <iframe class=\"pdf-shortcode-iframe\" src=\"https:\/\/docs.google.com\/viewer? url=https:\/\/myurl.com\/media\/$3&embedded=true"><\/iframe> <\/object>/gs;t' <<< "Hello, view this pdf [PDF='hello.pdf']
and then view this PDF [PDF='goodmorning.pdf']"
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