# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/(?:^.*StartToken \S+\s| EndToken.*$)//g;t' <<< "WordA1 wordA2 wordAN StartToken Skipword WordB1 WordB2 WordBN EndToken WordV1 WordCN"
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