# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/(https?:\\/\\/)?([w]{3}\.)?(\w*.\w*)([\\/\w]*)/$3/gmi;t' <<< "https://www.facebook.org/hello
http://www.xxxx.wordpress.com/hello
http://www.xxxx.yyy.zzz.wordpress.com/hello"
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