# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/(\w+)(?=outputtable).*/\1/gm;t' <<< "rfoutputtablep7q10000t20000c100
rfoutputtablep7q1000t20000c100
svmLinear2outputtablep7q20000t20000c100
svmLinear2outputtablep7q5000t20000c100"
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