how to use sed, awk, or gawk to print only what is matched?

Question

I see lots of examples and man pages on how to do things like search-and-replace using sed, awk, or gawk.

But in my case, I have a regular expression that I want to run

Answer 1

For awk. I would use the following script:

/.*abc([0-9]+)xyz.*/ {
            print $0;
            next;
            }
            {
            /* default, do nothing */
            }