# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/[\s\S]*(?:location="([^"]*)")[\s\S]*/$1/gm;t' <<< "<xxxx location=\"file path/level1/level1\" xxxx some=\"xxx\">
<xxxx location=\"file path/level1/level2\" xxxx some=\"xxx\">
<xxxx location=\"file path/level1/level3\" xxxx some=\"xxx\">"
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