# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/\/(\w+[[\/])/\/:\1/g;t' <<< "//party[@id='party1:abc']/abc:person[@id='Trader']/trade/abc:personId[@personIdScheme='urn:xyz:person-id:PEOPLESOFT']/text()"
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