2.6.3 FEATURE REQUEST: Extend --only-matching to accept submatch

[Jari Aalto]

[Cf. https://savannah.gnu.org/bugs/index.php?29827]

Manual page reads:

       -o, --only-matching
              Print only the matched (non-empty) parts  of  a  matching  line,
              with each such part on a separate output line.

FEATURE REQUEST

Extend the option to accept additional numeric argument to control the
submatch returned. (By default 0). This woudl make it possible to run:

    echo "Program version 1.12" | grep -E -o 1 "Program.*([0-9.]+)"

Jari