sed replace line with capture groups

Question

Is it possible with sed to replace a line with capture groups from the regex?

I have this regex, please note that this is fixed, I cannot change it.

si

Answer 1

Perl to the rescue!

perl -ne 'if (/(.*)simple sample (.*) with (.*)/) {
            print "$1$2\n";
          } else { print }'

Answer 2

Like this?

echo "This is just a simple sample line with some text" | \
  sed 's/simple sample \(.*\)/\n\1/;s/.*\n//'

The idea is simple: replace the whole regexp match with the captured group preceded by a newline. Then replace everything up to and including the first newline with nothing. Of course, you could use a marker other than the newline.