I don't understand what I'm missing here:
$ echo 'testing' | sed -E 's/([a-z]*)ing/\1ing/g' ing
I would expect the output to be
testing again, since
\1 should be
test? That input seems to have been swallowed - i.e. the group matched it - but why is
\1 not spitting it back out?
I am on macOS 10.12.2; using xonsh shell and GNU sed v4.3.